Question

Решите номер 7.Есть вложение.

Answer 1

$( frac{a+3b}{a^2-3ab}- frac{1}{a} ): frac{b}{3b-a} = frac{a+3b-a+3b}{a(a-3b)}cdot frac{3b-a}{b} = \ = frac{6b}{a(a-3b)}cdot frac{3b-a}{b} = frac{6b(3b-a)}{ab(a-3b)}= -frac{6}{a}= -frac{6}{7.5}= -frac{60}{75}=-frac{4}{5}=-0,8$