Question

Как получили y<1/5 ? (см картинку)

Answer 1

$\frac{2-y}{5y-1} \leq -0.2$ ⇒$\frac{2-y}{5y-1} +0.2\leq 0$ ⇒
$\frac{2-y+0.2(5y-1)}{5y-1} \leq 0$  ⇒$\frac{2-y+y-0.2}{5y-1} \leq 0$ 
⇒$\frac{1.8}{5y-1} \leq 0$  ⇒ $5y-1\ \textless \ 0$ ⇒
$5y\ \textless \ 1$ ⇒ $y\ \textless \ \frac{1}{5}$