Преобразуем в дробь

1. а) $$rac{5(x + y)}{8xy} \cdot \frac{4x^2}{7(x + y)} = \frac{5 \cdot 4 \cdot x^2 \cdot (x+y)}{8 \cdot 7 \cdot x \cdot y \cdot (x+y)} = \frac{20x^2(x+y)}{56xy(x+y)} = \frac{5x}{14y}$$
2. в) $$\frac{3x-6y}{xy} \cdot \frac{x^2}{xy - 2y^2} = \frac{3(x-2y)}{xy} \cdot \frac{x^2}{y(x - 2y)} = \frac{3 \cdot x^2 \cdot (x-2y)}{x \cdot y^2 \cdot (x-2y)} = \frac{3x}{y^2}$$
3. д) $$\frac{a^2-b^2}{4ab} \cdot \frac{8a}{3a+3b} = \frac{(a-b)(a+b)}{4ab} \cdot \frac{8a}{3(a+b)} = \frac{8a(a-b)(a+b)}{12ab(a+b)} = \frac{2(a-b)}{3b}$$