a) \(\frac{8}{40}+\frac{-14}{35}-\frac{12}{60}\)

= \(\frac{1}{5}-\frac{2}{5}-\frac{1}{5}\)

= \(\left(\frac{1}{5}-\frac{1}{5}\right)-\frac{2}{5}\)

= \(-\frac{2}{5}\)

b) 5/7.5/11 + 5/7.5/11 - 5/7.14/11

= 5/7.(5/11 + 5/11 - 14/11) 

= 5/7.(-4/11)

= -20/77

c) \(19\frac{5}{8}:\frac{7}{12}-15\frac{1}{4}:\frac{7}{12}\)

= \(\left(19\frac{5}{8}-15\frac{1}{4}\right):\frac{7}{12}\)

=  \(\frac{35}{8}:\frac{7}{12}\)

=  \(\frac{15}{2}\)

d) 2/5.1/3 - 2/15 : 1/5 + 3/5.1/3

= (2/5 + 3/5).1/3 - 2/15 . 5

= 1.1/3 - 2/3

= 1/3 - 2/3

= -1/3

e) \(\frac{4}{9}.19\frac{1}{3}-\frac{4}{9}.39\frac{1}{3}\)

= \(\frac{4}{9}.\left(19\frac{1}{3}-39\frac{1}{3}\right)\)

= \(\frac{4}{9}.\left(-20\right)\)

= \(\frac{-80}{9}\)

g) \(\frac{81.17-15.81}{81.17-81.15}\)

= 1

a)8/40+-14/35-12/60=1/5+(-2/5)-1/5=-2/5

b)5/7.5/11+5/7.5/11-5/7.14/11=5/7.(5/11+5/11-14/11)=5/7.-4/11=-20/77

c)19 5/8:7/12-15 1/4:7/12=(19 5/8-15 1/4):7/12=35/8.12/7=15/2

d)2/5.1/3-2/15:1/5+3/5.1/3=2/15-2/15.5/1+3/15=2/15.2/3+1/5=-5/15=-1/5

e)4/9.19 1/3-4/9.39 1/3=4/9.(19 1/3- 39 1/3)=4/9. 20=80/9

g)81.17-15.81/81.17-81.15=81.(17-15)-15.1.17=81.2-255=162-255=-90

Chúc bạn học giỏi!!! hihi

nhiều thế

sfdhg 

(26/19 - 7/19)x ( 8/11+3/11)

= 1x1 

=1

a) 12 + 3 = 15     15 + 4 = 19     8 + 2 = 10     14 + 3 = 17

15 - 3 = 12     19 - 4 = 15     10 - 2 = 8     17 - 3 = 14

b) 11 + 4 + 2 = 17     19 - 5 - 4 = 10     14 + 2 - 5 = 11

=-4/15 - 18/19-20/19-11/15

= (-4/15-11/15) - (18/19+20/19)

= -1 - 2

= - 3

\(\left(\frac{-4}{15}-\frac{18}{19}\right)-\left(\frac{20}{19}+\frac{11}{15}\right)=\frac{-4}{15}-\frac{18}{19}-\frac{20}{19}-\frac{11}{15}\)

\(=\left(\frac{-4}{15}-\frac{11}{15}\right)-\left(\frac{18}{19}+\frac{20}{19}\right)=\frac{-15}{15}-\frac{38}{19}=-1-2=-3\)

\(\frac{8}{27}+\frac{4}{15}+\frac{19}{27}+\frac{11}{15}\)

\(=\left(\frac{8}{27}+\frac{19}{27}\right)+\left(\frac{4}{15}+\frac{11}{15}\right)\)

\(=\frac{27}{27}+\frac{15}{15}\)

\(=1+1=2\)

8/27+4/15+19/27+11/15

=(8/27+19/27)+(4/15+11/5)

=27/27+15/15

=1+1

=2

\(\frac{8}{27}+\frac{4}{15}+\frac{19}{27}+\frac{11}{15}\)

\(=(\frac{8}{27}+\frac{19}{27})+(\frac{4}{15}+\frac{11}{15})\)

\(=1+1=2\)

\(a,\dfrac{9}{17}+\dfrac{15}{4}=\dfrac{36}{68}+\dfrac{255}{68}=\dfrac{291}{68}\\ b,\dfrac{19}{121}-\dfrac{1}{11}=\dfrac{19}{121}-\dfrac{11}{121}=\dfrac{8}{121}\\ c,\dfrac{4}{15}+3=\dfrac{4}{15}+\dfrac{45}{15}=\dfrac{49}{15}\\ d,3-\dfrac{5}{9}=\dfrac{27}{9}-\dfrac{5}{9}=\dfrac{22}{9}\)

\(a,\dfrac{9}{17}+\dfrac{15}{4}=\dfrac{36}{68}+\dfrac{255}{68}=\dfrac{291}{68}\)

\(b,\dfrac{19}{121}-\dfrac{1}{11}=\dfrac{19}{121}-\dfrac{11}{121}=\dfrac{8}{121}\)

\(c,\dfrac{4}{15}+3=\dfrac{4}{15}+\dfrac{3}{1}=\dfrac{4}{15}+\dfrac{45}{15}=\dfrac{49}{15}\)

\(d,3-\dfrac{5}{9}=\dfrac{3}{1}-\dfrac{5}{9}=\dfrac{27}{9}-\dfrac{5}{9}=\dfrac{22}{9}\)

`A) 9/17 + 15/4 = 36/68 + 255/68 = 291/68 `

` B) 19/121 - 1/11= 19/121 - 11/121 = 8/121 ` 

` C) 4/15 + 3 = 4/15 + 45/15 = 49/15 `

` D) 3 - 5/9 = 27/9 - 5/9 = 22/9 `