a) `1/3 - 1/4 : 2/5 = 1/3 - 5/8 = -7/24`

b) `6/7-(5/6+1/3)-(2/3+1/7) = 6/7-5/6-1/3-2/3-1/7`

`=(6/7-1/7)-(1/3+2/3)-5/6`

`=5/7-1-5/6`

`=-47/42`

c) `-5/9 . 2/5 + 4 5/9 + 5/9 . (-3/5)`

`= -5/9 . 2/5 + 4 + 5/9 + (-5/9) . 3/5`

`=-5/9 . (2/5 + 3/5-1) + 4`

`=-5/9 . 0 +4`

`=4`

d) 3 1/2 - (5 4/7 - 1 1/2) : 0,75`

`=7/2 - (39/7 - 3/2) : 3/4`

`= 7/2 - 57/14 : 3/4`

`=7/2 - 38/7`

`=-27/14`

De tke nma khonq bt lamm

Nguu

\(\dfrac{3}{7}+\dfrac{4}{1}=\dfrac{3}{7}+\dfrac{28}{7}=\dfrac{31}{7}\)

\(\dfrac{5}{9}\times3=\dfrac{5}{9}\times\dfrac{3}{1}=\dfrac{15}{9}=\dfrac{5}{3}\)

\(\dfrac{7}{8}-\dfrac{2}{9}=\dfrac{63}{72}-\dfrac{16}{72}=\dfrac{47}{72}\)

\(\dfrac{5}{1}-\dfrac{3}{4}=\dfrac{20}{4}-\dfrac{3}{4}=\dfrac{17}{4}\)

\(\dfrac{5}{7}:\dfrac{6}{1}=\dfrac{5}{7}\times\dfrac{1}{6}=\dfrac{5}{42}\)

\(\dfrac{5}{6}\times\dfrac{2}{7}=\dfrac{5\times2}{6\times7}=\dfrac{10}{42}=\dfrac{5}{21}\)

\(\dfrac{3}{1}+\dfrac{3}{4}=\dfrac{12}{4}+\dfrac{3}{4}=\dfrac{15}{4}\)

\(\dfrac{3}{5}\times\dfrac{4}{8}=\dfrac{3}{5}\times\dfrac{1}{2}=\dfrac{3\times1}{5\times2}=\dfrac{3}{10}\)

\(\dfrac{5}{1}:\dfrac{3}{8}=\dfrac{5}{1}\times\dfrac{8}{3}=\dfrac{40}{3}\)

a) \(\dfrac{3}{7}+4=\dfrac{3}{7}+\dfrac{4}{1}=\dfrac{3}{7}+\dfrac{28}{7}=\dfrac{31}{7}\)

b) \(\dfrac{5}{9}\times3=\dfrac{5\times3}{9}=\dfrac{15}{9}=\dfrac{5}{3}\)

c) \(\dfrac{7}{8}-\dfrac{2}{9}=\dfrac{63}{72}-\dfrac{16}{72}=\dfrac{47}{72}\)

d) \(5-\dfrac{3}{4}=\dfrac{5}{1}-\dfrac{3}{4}=\dfrac{20}{4}-\dfrac{3}{4}=\dfrac{17}{4}\)

e) \(\dfrac{5}{7}:6=\dfrac{5}{7}:\dfrac{6}{1}=\dfrac{5}{7}\times\dfrac{1}{6}=\dfrac{5}{42}\)

f) \(\dfrac{5}{6}\times\dfrac{2}{7}=\dfrac{5\times2}{6\times7}=\dfrac{10}{42}=\dfrac{5}{21}\)

g) \(3+\dfrac{3}{4}=\dfrac{3}{1}+\dfrac{3}{4}=\dfrac{12}{4}+\dfrac{3}{4}=\dfrac{15}{4}\)

h) \(\dfrac{3}{5}\times\dfrac{4}{8}=\dfrac{3\times4}{5\times8}=\dfrac{12}{40}=\dfrac{3}{10}\)

i) \(5:\dfrac{3}{8}=\dfrac{5}{1}:\dfrac{3}{8}=\dfrac{5}{1}\times\dfrac{8}{3}=\dfrac{40}{3}\)

\(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\)

\(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{49}{30}\)

\(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{1}{5}\)

\(\dfrac{8}{5}x\dfrac{5}{8}=\dfrac{1}{1}=1\)

\(\dfrac{6}{7}x\dfrac{4}{7}=\dfrac{24}{49}\)

\(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}x\dfrac{5}{4}=\dfrac{1}{1}=1\)

\(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}x\dfrac{5}{5}=\dfrac{1}{1}=1\)

1) \(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{1+2}{3}=\dfrac{3}{3}=1\)

2) \(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{24+25}{30}=\dfrac{49}{30}\)

3) \(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{4-3}{5}=\dfrac{1}{5}\)

4) \(\dfrac{9}{8}-\dfrac{4}{2}=\dfrac{9}{8}-2=\dfrac{9}{8}-\dfrac{16}{8}=-\dfrac{7}{8}\)

5) \(\dfrac{8}{5}\times\dfrac{5}{8}=\dfrac{8\times5}{5\times8}=\dfrac{40}{40}=1\)

6) \(\dfrac{6}{7}\times\dfrac{4}{7}=\dfrac{6\times4}{7}=\dfrac{24}{7}\)

7) \(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}\times\dfrac{5}{4}=\dfrac{4\times5}{5\times4}=\dfrac{20}{20}=1\)

8) \(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}\times\dfrac{5}{5}=\dfrac{5\times5}{5\times5}=\dfrac{25}{25}=1\)

?

a. 7/8 x 2/5 =7/20

b.9/4-5/6=17/12

c.4/7x2/5=8/35

d.3/5+2=13/5

e. 4-3/5=17/5

g.3x4/9=4/3

h.9/5:2=9/10

a) \(\dfrac{14}{40}=\dfrac{7}{20}\)

b) \(\dfrac{27}{12}-\dfrac{10}{12}=\dfrac{17}{12}\)

c) \(\dfrac{8}{35}\)

d) \(\dfrac{3}{5}+\dfrac{10}{5}=\dfrac{13}{5}\)

e) \(\dfrac{20}{5}-\dfrac{3}{5}=\dfrac{17}{5}\)

g) \(\dfrac{12}{9}=\dfrac{4}{3}\)

h) \(\dfrac{9}{5}x\dfrac{1}{2}=\dfrac{9}{10}\)

`@LQuyen`

\(\dfrac{7}{8}\times\dfrac{2}{5}=\dfrac{14}{40}\)

\(\dfrac{9}{4}-\dfrac{5}{6}=\dfrac{54}{24}-\dfrac{20}{24}=\dfrac{34}{24}\)

\(\dfrac{4}{7}\times\dfrac{2}{5}=\dfrac{8}{35}\)

\(\dfrac{3}{5}+\dfrac{2}{1}=\dfrac{3}{5}+\dfrac{10}{5}=\dfrac{13}{5}\)

\(\dfrac{4}{1}-\dfrac{3}{5}=\dfrac{20}{5}-\dfrac{3}{5}=\dfrac{17}{5}\)

\(3\times\dfrac{4}{9}=\dfrac{12}{9}\)

\(\dfrac{9}{5}:2=\dfrac{9}{10}\)

\(a.\dfrac{2}{3}+\dfrac{4}{3}:\dfrac{-2}{3}=\dfrac{2}{3}+\left(-2\right)=\dfrac{-4}{3}\)

\(b.3\dfrac{4}{5}-\left(2\dfrac{1}{4}+1\dfrac{4}{5}\right)\\ =3\dfrac{4}{5}-2\dfrac{1}{4}-1\dfrac{4}{5}\\ =\left(3\dfrac{4}{5}-1\dfrac{4}{5}\right)-2\dfrac{1}{4}\\ =2-2\dfrac{1}{4}=\dfrac{1}{4}\)

\(c.\dfrac{-3}{5}.\dfrac{4}{7}+\dfrac{3}{7}.\dfrac{-3}{5}+\dfrac{3}{5}\\ =\dfrac{-3}{5}\left(\dfrac{4}{7}+\dfrac{3}{7}\right)+\dfrac{3}{5}\\ =\dfrac{-3}{5}+\dfrac{3}{5}=0\)

a) \(\dfrac{2}{5}+\dfrac{4}{3}:\dfrac{-2}{3}\)

\(=\dfrac{2}{5}+\dfrac{4}{3}.\dfrac{-3}{2}\)

\(=\dfrac{2}{5}+-2\)

\(=\dfrac{2}{5}+\dfrac{-10}{5}\)

\(=\dfrac{-8}{5}\)

a) \(\dfrac{2}{5}+\dfrac{4}{3}:\dfrac{-2}{3}=\dfrac{2}{5}+-2=\dfrac{-8}{5}\)  

b) \(3\dfrac{4}{5}-\left(2\dfrac{1}{4}+1\dfrac{4}{5}\right)=\dfrac{19}{5}-\dfrac{9}{4}-\dfrac{9}{5}=\left(\dfrac{19}{5}-\dfrac{9}{5}\right)-\dfrac{9}{4}=2-\dfrac{9}{4}=\dfrac{-1}{4}\) 

c) \(\dfrac{-3}{5}.\dfrac{4}{7}+\dfrac{3}{7}.\dfrac{-3}{5}+\dfrac{3}{5}\) 

\(=\dfrac{-3}{5}.\left(\dfrac{4}{7}+\dfrac{3}{7}\right)+\dfrac{3}{5}\) 

\(=\dfrac{-3}{5}.1+\dfrac{3}{5}\) 

\(=\dfrac{-3}{5}+\dfrac{3}{5}\) 

\(=0\) 

d) \(40\%-1\dfrac{5}{7}:\dfrac{3}{7}+\left|\dfrac{-9}{5}\right|\) 

\(=\dfrac{2}{5}-\dfrac{12}{7}:\dfrac{3}{7}+\dfrac{9}{5}\) 

\(=\dfrac{2}{5}-4+\dfrac{9}{5}\) 

\(=\dfrac{-9}{5}\)

= 3/10 + 4/7 . 5/4 - 1/10 
= 3/10 + 5/7 - 1/70 
= 1.

\(\dfrac{3}{10}+\dfrac{4}{7}.\dfrac{5}{4}-\dfrac{1}{70}=\dfrac{3}{10}+\dfrac{5}{7}-\dfrac{1}{70}=\dfrac{21}{70}+\dfrac{50}{70}-\dfrac{10}{70}=\dfrac{70}{70}=1\)

1) \(=\dfrac{1}{2}.\dfrac{3}{5}+\dfrac{4}{7}.\dfrac{5}{4}-\dfrac{1}{70}\)

\(=\dfrac{3}{10}+\dfrac{5}{7}-\dfrac{1}{70}\)

\(=\dfrac{21}{70}+\dfrac{50}{70}-\dfrac{1}{70}\)

\(=1\)

2)

\(=\left(\dfrac{30}{45}+\dfrac{9}{45}-\dfrac{20}{45}\right):\left(\dfrac{15}{45}+\dfrac{18}{45}-\dfrac{30}{45}\right)\)

\(=\dfrac{19}{45}:\dfrac{1}{45}\)

\(=\dfrac{19}{45}.45\)

\(=19\)

\(\dfrac{2}{5}\times\dfrac{3}{4}-\dfrac{1}{8}=\dfrac{1}{5}\times\dfrac{3}{2}-\dfrac{1}{8}=\dfrac{3}{10}-\dfrac{1}{8}=\dfrac{24}{80}-\dfrac{10}{80}=\dfrac{14}{80}=\dfrac{7}{40}\\ \dfrac{4}{3}+\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{3}-\dfrac{1}{5}=\dfrac{25}{15}-\dfrac{3}{15}=\dfrac{22}{15}\\ \dfrac{9}{20}-\dfrac{3}{5}\times\dfrac{1}{4}=\dfrac{9}{20}-\dfrac{3}{20}=\dfrac{6}{20}=\dfrac{3}{10}\\ \dfrac{2}{8}+\dfrac{2}{3}:\dfrac{4}{5}=\dfrac{2}{8}+\dfrac{2}{3}\times\dfrac{5}{4}=\dfrac{2}{8}+\dfrac{1}{3}\times\dfrac{5}{2}=\dfrac{2}{8}+\dfrac{5}{6}=\dfrac{1}{4}+\dfrac{5}{6}=\dfrac{6}{24}+\dfrac{20}{24}=\dfrac{26}{24}=\dfrac{13}{12}\)

\(e.\dfrac{7}{10}\cdot\dfrac{-3}{5}+\dfrac{7}{10}\cdot\dfrac{-2}{5}-\dfrac{3}{10}\)

\(=\dfrac{7}{10}\cdot\left[\left(\dfrac{-3}{5}\right)+\left(\dfrac{-2}{5}\right)\right]-\dfrac{3}{10}\)

\(=\dfrac{7}{10}\cdot1-\dfrac{3}{10}=\dfrac{4}{10}=\dfrac{2}{5}\)

\(f.\dfrac{-3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+2\dfrac{3}{7}\)

\(=\dfrac{-3}{7}\cdot\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{17}{3}\)

\(=\dfrac{-3}{7}\cdot1+\dfrac{17}{3}=\dfrac{-9}{21}+\dfrac{119}{21}=\dfrac{110}{21}\)

\(g.\dfrac{5}{9}\cdot\dfrac{10}{17}+\dfrac{5}{9}\cdot\dfrac{9}{17}-\dfrac{5}{9}\cdot\dfrac{2}{17}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{10}{17}+\dfrac{9}{17}-\dfrac{2}{17}\right)\)

\(=\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)

a: =-10/21

b: =-5/27

c: =-20/20=-1

d: =-15/105=-1/7

e: =-63/63=-1

\(\dfrac{10}{21}\)

\(\dfrac{5}{27}\)

\(1\)

\(\dfrac{1}{7}\)

\(1\)

a: \(=\dfrac{-8}{9}-\dfrac{6}{5}+\dfrac{8}{9}=-\dfrac{6}{5}\)

c: \(=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)