51 и 52, пожалуйста ❤❤❤

Решите задачу:

$51.\; \; \Big (\frac{a+2b}{a^2-2ab}-\frac{1}{a}\Big ):\frac{b}{2b-a}=\Big (\frac{a+2b}{a(a-2b)}-\frac{1}{a}\Big ):\frac{b}{2b-a}=\\\\=\frac{a+2b-(a-2b)}{a(a-2b)}\cdot \frac{-(a-2b)}{b}=\frac{4b}{a(a-2b)}\cdot \frac{-(a-2b)}{b}=-\frac{4}{a}=-\frac{4}{1,6}=-2,5$

$52.\; \; \Big (\frac{a+b}{a^2-ab}-\frac{1}{a}\Big ):\frac{b}{b-a}=\Big (\frac{a+b}{a(a-b)}-\frac{1}{a}\Big ):\frac{b}{b-a}=\\\\=\frac{a+b-(a-b)}{a(a-b)}\cdot \frac{b-a}{b}=\frac{2b}{a(a-b)}\cdot \frac{-(a-b)}{b}=-\frac{2}{a}=-\frac{2}{0,5}=-4$