Tìm x: a) -2/3 x + 1/5 = 3/10 b) -1/2 + 1/3 : x =1 c) 5 3/8 - 4/5 (x-1)

* Hướng dẫn giải

a) 

$\begin{array}{l}\frac{-2}{3}x+\frac{1}{5}=\frac{3}{10}\\ \frac{-2}{3}x=\frac{1}{10}\\ x=\frac{1}{10}:\frac{-2}{3}\\ x=\frac{-3}{20}\end{array}$

b)

$\begin{array}{l}\frac{-1}{2}+\frac{1}{3}:x=1\\ \frac{1}{3}:x=1+\frac{1}{2}\\ \frac{1}{3}:x=\frac{3}{2}\\ x=\frac{1}{3}:\frac{3}{2}\\ x=\frac{2}{9}\end{array}$

c) 

$\begin{array}{l}5\frac{3}{8}-\frac{4}{5}\left(x-1\right)=4\frac{3}{8}\\ \frac{4}{5}\left(x-1\right)=5\frac{3}{8}-4\frac{3}{8}\\ \frac{4}{5}\left(x-1\right)=1\\ x-1=\frac{5}{4}\\ x=\frac{9}{4}\end{array}$