Question

Помогите пожалуйста.

Answer 1

$cfrac{3y}{5x}- cfrac{9y^2+25x^2}{15xy}+ cfrac{5x-3y}{3y}= cfrac{3y*3y-(9y^2+25x^2)+5x(5x-3y)}{15xy}= \ \ \ = cfrac{9y^2-9y^2-25x^2+25x^2-15xy}{15xy}=cfrac{-15xy}{15xy}=-1$