б) \frac{3}{5}y = 2\frac{9}{10} - \frac{1}{5};

б) $$ \frac{3}{5}y = 2\frac{9}{10} - \frac{1}{5} $$

$$ \frac{3}{5}y = \frac{29}{10} - \frac{1}{5} $$

$$ \frac{3}{5}y = \frac{29}{10} - \frac{1 \cdot 2}{5 \cdot 2} $$

$$ \frac{3}{5}y = \frac{29}{10} - \frac{2}{10} $$

$$ \frac{3}{5}y = \frac{27}{10} $$

$$ y = \frac{27}{10} : \frac{3}{5} $$

$$ y = \frac{27}{10} \cdot \frac{5}{3} $$

$$ y = \frac{27 \cdot 5}{10 \cdot 3} $$

$$ y = \frac{9 \cdot 1}{2 \cdot 1} $$

$$ y = \frac{9}{2} $$

$$ y = 4\frac{1}{2} $$

Ответ: 4$$\frac{1}{2}$$