\(a,\frac{2}{7}:\frac{4}{5}=\frac{2}{7}\times\frac{5}{4}=\frac{10}{28}=\frac{5}{14}\)

\(b,\frac{3}{8}:\frac{9}{4}=\frac{3}{8}\times\frac{4}{9}=\frac{12}{72}=\frac{1}{6}\)

\(c,\frac{8}{21}:\frac{4}{7}=\frac{8}{21}\times\frac{7}{4}=\frac{56}{84}=\frac{2}{3}\)

\(d,\frac{5}{8}:\frac{15}{8}=\frac{5}{8}\times\frac{8}{15}=\frac{40}{120}=\frac{1}{3}\)

A,\(\frac{2}{7}:\frac{4}{5}=\frac{2}{7}\times\frac{5}{4}=\frac{10}{28}=\frac{5}{14}\)

B,\(\frac{3}{8}:\frac{9}{4}=\frac{3}{8}\times\frac{4}{9}=\frac{12}{72}=\frac{1}{6}\)

C.\(\frac{8}{21}:\frac{4}{7}=\frac{8}{21}\times\frac{7}{4}=\frac{56}{84}=\frac{2}{3}\)

D.\(\frac{5}{8}:\frac{15}{8}=\frac{5}{8}\times\frac{8}{15}=\frac{40}{120}=\frac{1}{3}\)

Đúng 100%

a, \(\frac{2}{7}:\frac{4}{5}=\)\(\frac{2}{7}x\)\(\frac{5}{4}\)\(\frac{10}{28}=\frac{5}{14}\)

b,\(\frac{3}{8}:\frac{9}{4}\)\(=\frac{3}{8}x\)\(\frac{4}{9}\)\(=\frac{12}{72}=\frac{1}{6}\)

c,\(\frac{8}{21}:\frac{4}{7}\)\(=\frac{8}{21}x\)\(\frac{7}{4}\)\(=\frac{56}{84}=\frac{2}{3}\)

d,\(\frac{5}{8}:\frac{15}{8}\)\(\frac{5}{8}x\)\(\frac{8}{15}=\frac{40}{120}=\frac{1}{3}\)

tk giup mk nha

BÀI 1:

a)    \(\frac{4}{5}+\frac{3}{8}+\frac{1}{4}\)

\(=\frac{32}{40}+\frac{15}{40}+\frac{10}{40}\)

\(=\frac{32+15+10}{40}\)\(=\frac{57}{40}\)

b)    \(\frac{5}{9}+\frac{2}{3}+\frac{1}{2}\)

\(=\frac{10}{18}+\frac{12}{18}+\frac{9}{18}\)

\(=\frac{10+12+9}{18}=\frac{31}{18}\)

bài 23,, 5 nữa

1. 

a.57/40

b.31/18

a, \(\dfrac{20}{15}=\dfrac{4}{3}\)

b, \(\dfrac{6}{15}=\dfrac{2}{5}\)

c, \(\dfrac{42}{30}=\dfrac{7}{5}\)

d, \(\dfrac{40}{35}=\dfrac{8}{7}\)

e, \(\dfrac{42}{42}=1\)

g, \(\dfrac{54}{10}=\dfrac{27}{5}\)

h, \(\dfrac{12}{15}\)

k đúng để nhận câu trả lời
 

a)1/3

b)4/5

c)1

d)2 nha

a)=2/3-1/3= 1/3

b)=7/5-3/5= 4/5

c)=3/2-1/2= 2/2=1

d)=11/4-3/4= 8/4= 2

a) \(\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{1}{3}\)

b) \(\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{4}{5}\)

c) \(\frac{3}{2}-\frac{4}{8}=\frac{3}{2}-\frac{1}{2}=1\)

d) \(\frac{11}{4}-\frac{6}{8}=\frac{11}{4}-\frac{3}{4}=2\)

Bài 1: Tính

\(a.\frac{15}{16}-\frac{7}{16}=\frac{15-7}{16}=\frac{8}{16}=\frac{1}{2}\)

\(b.\frac{7}{4}-\frac{3}{4}=\frac{7-3}{4}=\frac{4}{4}=1\)

\(c.\frac{9}{5}-\frac{3}{5}=\frac{9-3}{5}=\frac{6}{5}\)

\(d.\frac{17}{49}-\frac{12}{49}=\frac{17-12}{49}=\frac{5}{49}\)

Bài 2:Rút gọn rồi tính

\(a.\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{2-1}{3}=\frac{1}{3}\)

\(b.\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{7-3}{5}=\frac{4}{5}\)

Học tốt. K cho mik nha

Trl :

Bạn kia làm đúng rồi nhé !

Học tốt nhé bạn @

40000000000000+09999999999999999999999=.....,..............,.......,........

a) \(\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{2-1}{3}=\frac{1}{3}\)

b) \(\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{7-3}{5}=\frac{4}{5}\)

c) \(\frac{3}{2}-\frac{4}{8}=\frac{3}{2}-\frac{1}{2}=\frac{3-1}{2}=\frac{2}{2}=1\)

d) \(\frac{11}{4}-\frac{6}{8}=\frac{11}{4}-\frac{3}{4}=\frac{11-3}{4}=\frac{8}{4}=2\)

Xhhvxbmntgbvsjk

`2/5 + 9/15= 2/5 + 3/5=5/5=1`

`15/45 + 25/30= 1/3 + 5/6= 2/6+5/6=7/6`

`28/32 + 45/72=7/8+ 5/8=12/8=3/2`

`8/28 + 5/30= 2/7 + 1/6= 12/42 + 7/42= 19/42`