2х − 5 = х + 2
2х − х = 2 + 5
х = 7

$\frac{2}{5}х + \frac{3}{5} = \frac{1}{5}х$
$\frac{2}{5}х - \frac{1}{5}х = -\frac{3}{5}$
$\frac{1}{5}х = -\frac{3}{5}$
$х = -\frac{3}{5} : \frac{1}{5}$
$х = -\frac{3}{5} * \frac{5}{1}$
х = −3

0,5у − 0,6 = 0,1у + 0,2
0,5y − 0,1y = 0,2 + 0,6
0,4y = 0,8
y = 2

$\frac{2}{3}z = \frac{2}{9}z - \frac{4}{9}$
$\frac{6}{9}z - \frac{2}{9}z = -\frac{4}{9}$
$\frac{4}{9}z = -\frac{4}{9}$
$z = -\frac{4}{9} : \frac{4}{9}$
z = −1