-8/12= -2/3

15/-60= 1/-4

-16/-72= 2/9

35/14.15= 1/6

-8/12 rút gọn bằng-2/3; 15/-60 =-1/4; -16/-72=2/9;35/14.15=1/6

-2/3

1/-4

2-9

1/6

\(\dfrac{-8}{12}=\dfrac{-8:4}{12:4}=\dfrac{-2}{3}\\ \dfrac{15}{-60}=\dfrac{15:15}{-60:15}=\dfrac{1}{-4}\\ \dfrac{-16}{-72}=\dfrac{-16:\left(-8\right)}{-72:\left(-8\right)}=\dfrac{2}{9}\\ \dfrac{35}{14.15}=\dfrac{5.7}{7.2.5.3}=\dfrac{1}{2.3}=\dfrac{1}{6}\)

-2/3

-1/4

2/9

1/6

-8/12= -2/3

15/-60= 1/-4

-16/-72= 2/9

35/14.15= 1/6

\(a.-\dfrac{8}{12}=\dfrac{-2\cdot4}{4\cdot3}=-\dfrac{2}{3}\)

\(b.\dfrac{15}{-60}=\dfrac{15}{15\cdot-4}-\dfrac{1}{4}\)

\(c.\dfrac{-16}{-72}=\dfrac{-2\cdot8}{-9\cdot8}=\dfrac{2}{9}\)

\(d.\dfrac{35}{14\cdot15}=\dfrac{7\cdot5}{7\cdot2\cdot5\cdot3}=\dfrac{1}{6}\)

\(\dfrac{8}{12}\)=\(\dfrac{2}{31}\)

\(\dfrac{15}{-60}\)=\(\dfrac{-1}{4}\)

\(\dfrac{-16}{72}\)=\(\dfrac{-2}{9}\)

\(\dfrac{35}{14.15}=\dfrac{35}{210}=\dfrac{1}{6}\)

28/42=2/3

60/135=4/9

288/180=8/5

`28/42 = (28:14)/(42:14) = 2/3`

`60/135 = (60:15)/(135 : 15)=4/9`

`288/180 = (288:36)/(180:36) = 8/5`

\(\dfrac{50}{60}=\dfrac{5}{6}\)
\(\dfrac{33}{11}=3\)
\(\dfrac{16}{60}=\dfrac{4}{15}\)
\(\dfrac{42}{22}=\dfrac{21}{11}\)

chia là gì z

50/60=5/6

33/11=3

16/60=4/15

42/22=21/11

HT ☘

\(\dfrac{-63}{72}=\dfrac{-7}{8}\)

\(\dfrac{20}{-140}=\dfrac{-1}{7}\)

\(\dfrac{3.10}{5.24}=\dfrac{30}{120}=\dfrac{1}{4}\)

\(\dfrac{3.7.11}{22.9}=\dfrac{231}{198}=\dfrac{7}{6}\)

\(\dfrac{8.5-8.2}{16}=\dfrac{24}{16}=\dfrac{3}{2}\)

\(\dfrac{11.4-11}{2-13}=\dfrac{33}{-11}=-3\)

Bài 1:

a) \(\frac{13.23-13}{26.21+26}\)=\(\frac{13.22}{26.22}\)=\(\frac{13}{26}\)=\(\frac{1}{2}\)

b) \(\frac{16.21-16}{4.19+4}\)=\(\frac{16.20}{4.20}\)=\(\frac{16}{4}\)= 4

b - a = 18

=> b = a + 18

thay vào ta đc phân số : a/a + 18 = 5/7

=> 7a = 5a + 90

=> 2a = 90

=> a = 45

vậy ps cần tìm là  45/63

Tử số a là: \(18\div\left(7-5\right)\times5=45\)

Mẫu số b là: \(45+18=63\) 

=> Vậy phân số đã cho là: \(\frac{45}{63}\)