1 / 7/4 - y . 5/6 = 1/2 + 1/3

     7/4 - 5/6y = 5/6

    5/6y = 7/4 - 5/6 

    5/6y = 11/12

    y = 11/12 : 5/6 

    y = 11/10

2 . 136 là số chia 9 dư 1 

=> y = 136 - 1 = 135

3 . Dựa theo quy luật của dãy thì số tiếp theo là : 

    1/16 : 2 = 1/32 

1: y = \(\frac{11}{10}\)

2: Y = 135

3: Số hạng tiếp theo của dãy: \(\frac{1}{32}\)

7/4-y x 5/6 = 1/2+1/3

7/4-y x 5/6=5/6

      y x 5/6=7/4-5/6

      y x 5/6=11/12

               y=11/12 : 5/6

               y=11/10

\(\frac{7}{4}-y\times\frac{5}{6}=\frac{1}{2}+\frac{1}{3}\)

\(\frac{7}{4}-y\times\frac{5}{6}=\frac{5}{6}\)

\(\frac{7}{4}-y=\frac{5}{6}\div\frac{5}{6}\)

\(\frac{7}{4}-y=1\)

\(y=1+\frac{7}{4}\)

\(y=\frac{11}{4}\)

\(a,y+\dfrac{2}{3}=\dfrac{5}{2}\)

\(y=\dfrac{5}{2}-\dfrac{2}{3}\)

\(y=\dfrac{15}{6}-\dfrac{4}{6}\)

\(y=\dfrac{11}{6}\)

\(b,3\dfrac{4}{5}-y=\dfrac{18}{5}\)

\(y=3\dfrac{4}{5}-\dfrac{18}{5}\)

\(y=\dfrac{19}{5}-\dfrac{18}{5}\)

\(y=\dfrac{1}{5}\)

\(c,y-4\dfrac{5}{6}=2\dfrac{1}{6}+\dfrac{5}{6}\)

\(y-\dfrac{29}{6}=\dfrac{13}{6}+\dfrac{5}{6}\)

\(y-\dfrac{29}{6}=\dfrac{18}{6}\)

\(y=\dfrac{18}{6}+\dfrac{29}{6}\)

\(y=\dfrac{47}{6}\)

a) \(\frac{7}{10}-y\cdot\frac{3}{4}=\frac{1}{5}\)

\(y\cdot\frac{3}{4}=\frac{7}{10}-\frac{1}{5}\)

\(y\cdot\frac{3}{4}=\frac{1}{2}\)

\(y=\frac{1}{2}:\frac{3}{4}\)

\(y=\frac{1}{2}\cdot\frac{4}{3}\)

\(y=\frac{2}{3}\)

b) \(\frac{5}{6}:\left(y+\frac{7}{9}\right)=\frac{3}{4}\)

\(y+\frac{7}{9}=\frac{5}{6}:\frac{3}{4}\)

\(y+\frac{7}{9}=\frac{5}{6}\cdot\frac{4}{3}\)

\(y+\frac{7}{9}=\frac{10}{9}\)

\(y=\frac{10}{9}-\frac{7}{9}\)

\(y=\frac{3}{9}=\frac{1}{3}\)

**** !

a, \(\frac{7}{10}-y\times\frac{3}{4}=\frac{1}{5}\)

\(\Rightarrow y\times\frac{3}{4}=\frac{7}{10}-\frac{1}{5}\)

\(\Rightarrow y\times\frac{3}{4}=\frac{1}{2}\)

\(\Rightarrow y=\frac{1}{2}\div\frac{3}{4}\)

\(\Rightarrow y=\frac{1}{3}\)

b, \(\frac{5}{6}\div\left(y+\frac{7}{9}\right)=\frac{3}{4}\)

\(\Rightarrow y+\frac{7}{9}=\frac{5}{6}\div\frac{3}{4}\)

\(\Rightarrow y+\frac{7}{9}=\frac{10}{9}\)

\(\Rightarrow y=\frac{10}{9}-\frac{7}{9}\)

\(\Rightarrow y=\frac{1}{3}\)

7/4-x*5/6=1/2+1/3

7/4-x*5/6=5/6

X=5/6:5/6

X=7/4-1

X=3/4

Chúc bạn HK tốt

a) 7/10 - y × 3/4 = 1/5

                y × 3/4 = 7/10 - 1/5

                y × 3/4 = 1/2

                          y = 1/2 : 3/4

                          y = 2/3. Vậy y = 2/3

b) 5/6 : ( y + 7/9 ) = 3/4

                  y + 7/9 = 5/6 : 3/4

                  y + 7/9 = 10/9

                            y. = 10/9 - 7/9

                            y = 1/3. Vậy y = 1/3

\(\frac{7}{10}\)- y * \(\frac{3}{4}\)= \(\frac{1}{5}\)

y * \(\frac{3}{4}\)= \(\frac{7}{10}\)- \(\frac{1}{5}\)

y * \(\frac{3}{4}\)= \(\frac{1}{2}\)

y = \(\frac{1}{2}\): \(\frac{3}{4}\)

y = \(\frac{2}{3}\)

Vậy y = \(\frac{2}{3}\)

\(\frac{5}{6}\): ( y + \(\frac{7}{9}\)) = \(\frac{3}{4}\)

y + \(\frac{7}{9}\) = \(\frac{5}{6}\): \(\frac{3}{4}\)

y + \(\frac{7}{9}\) = \(\frac{10}{9}\)

y = \(\frac{10}{9}\)- \(\frac{7}{9}\)

y = \(\frac{3}{9}\)

Vậy y = \(\frac{3}{9}\)