a) y + 3/7 x 21/9 = 5

      y + 3/7 x 7/3 = 5

      y + 1             = 5

            y             = 4

b) y  x 3/5 - 1/2 = 4/5

    y x 3/5          = 4/5 + 1/2

    y x 3/5          = 13/10

    y                   = 13/6

c) 9/8 - y + 2/5 = 1/4

            y - 2/5  = 9 /8 - 1/4

            y - 2/5  = 7/8

                   y   = 51/40 

d) y - 6/5 : 2/3 = 5/6

    y - 9/5         = 5/6

          y           = 79/30

e) y : 7/8 + 3/4 = 7/4

    y : 7/8          = 1

          y            = 7/8

\(y+\frac{3}{7}\times\frac{21}{9}=5\)

\(y+\frac{3}{7}\times\frac{7}{3}=5\)

\(y+1=5\)

\(\Rightarrow y=4\)

\(y\times\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{1}{1}\)

\(y\times\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{4}{4}\)

\(y\times\dfrac{2}{3}=\dfrac{5}{4}\)

\(y=\dfrac{5}{4}:\dfrac{2}{3}\)

\(y=\dfrac{5}{4}\times\dfrac{3}{2}\)

\(y=\dfrac{15}{8}\)

\(\frac{1,3}{4}\times8-y=1\frac{2}{5}\)

\(\frac{13}{40}\times8-y=\frac{7}{5}\)

\(\frac{13}{5}-y=\frac{7}{5}\)

\(y=\frac{13}{5}-\frac{7}{5}\)

\(y=\frac{6}{5}\)

b) \(\frac{2,3}{4}\div\frac{2}{4}+y=\frac{19}{15}\)

\(\frac{23}{40}\times2+y=\frac{19}{15}\)

\(\frac{23}{20}+y=\frac{19}{15}\)

\(y=\frac{19}{15}-\frac{23}{20}\)

\(y=\frac{7}{60}\)

3/5 x y + 1/2 : 5/3 - 5/4 = 1/2 x 1/3

3/5xy +3/10 -5/4 =1/6

3/5xy=1/6 -3/10+5/4=67/60

y= 67/60:3/5=67/36

bài 1

A)37/60

B)13/45

C)1/4

bài 2

a)42/25:y/5=5/6

y=10,08

b)27/y:9/4=3/7

y=28

help me tui tick cho

a) \(y\times\dfrac{3}{4}=\dfrac{2}{5}\)

\(y=\dfrac{2}{5}:\dfrac{3}{4}\\ y=\dfrac{8}{15}\)

b) \(y:\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{7}{8}\)

\(y:\dfrac{2}{3}=\dfrac{7}{8}+\dfrac{2}{5}\\ y:\dfrac{2}{3}=\dfrac{51}{40}\\ y=\dfrac{51}{40}\times\dfrac{2}{3}\\ y=\dfrac{17}{20}\)

a) y = 5/14 : 6/7

y = 5/12 

vậy y = 5/12

b) y = 4/9 x 2/3 

y = 8/27 

vậy t = 8/27

c) y = 1/2 - 3/10 

y = 1/5

vậy y = 1/5

d) y = 5/6 - 1/3

y = 1/2

vậy y = 1/2

bài 1 :

\(\frac{5}{12}\) + \(\frac{1}{3}\) = \(\frac{5}{12}\) + \(\frac{4}{12}\) = \(\frac{5+4}{12}\) = \(\frac{9}{12}\) = \(\frac{3}{4}\)

1 - \(\frac{3}{4}\) = \(\frac{4}{4}\) - \(\frac{3}{4}\) = \(\frac{4-3}{4}\) = \(\frac{1}{4}\)

2 x \(\frac{3}{11}\) = \(\frac{2x3}{11}\) = \(\frac{6}{11}\)

\(\frac{8}{7}\): 4 = \(\frac{8}{7x4}\) = \(\frac{8}{28}\) = \(\frac{2}{7}\)

bài 2 :

\(\frac{2}{5}\) : y = \(\frac{1}{3}\) 

           y = \(\frac{2}{5}\) : \(\frac{1}{3}\)

           y = \(\frac{6}{5}\) 

y : \(\frac{7}{11}\) = 22

y             = 22 x \(\frac{7}{11}\)

y             = 14

ai thấy đúng tk nha

5/12 + 1/3 = 3/4

1 - 3/4 = 1/4

2 x 3/11 = 6/11

8/7 : 4 = 2/7

Tìm y

2/5 : y = 1/3

y =2/5 : 1/3

y = 6/5

y : 7/11 = 22

y = 22 x 7/11

y = 2/7

\(\frac{2}{3}x\frac{4}{y}=\frac{4}{45}:\frac{1}{5}\)\(=\frac{4}{15}\)

\(\frac{4}{y}=\frac{4}{15}:\frac{2}{3}\)\(=\frac{2}{5}\)

y=4:\(\frac{2}{5}\)    y=10

\(\frac{3}{4}x\frac{y}{5}=\frac{15}{4}\)

\(\frac{y}{5}=\frac{15}{4}:\frac{3}{4}=5\)

y=5x5=25