Tìm x, biết a) x/2 - 2/5 = 1/10 b) 15/x - 1/3 = 28/51

* Hướng dẫn giải

a)

$\begin{array}{l}\frac{x}{2}-\frac{2}{5}=\frac{1}{10}\\ \frac{x}{2}=\frac{1}{10}+\frac{2}{5}\\ \frac{x}{2}=\frac{1}{10}+\frac{4}{10}\\ \frac{x}{2}=\frac{1}{2}\\ \Rightarrow x=1\end{array}$

b)

$\begin{array}{l}\frac{15}{x}-\frac{1}{3}=\frac{28}{51}\\ \frac{15}{x}=\frac{28}{51}+\frac{1}{3}\\ \frac{15}{x}=\frac{28}{51}+\frac{17}{51}\\ \frac{15}{x}=\frac{15}{17}\\ \Rightarrow x=17\end{array}$