Выполните действия: Помогите!

А)
$\frac{2x}{2(x-3)} - \frac{9}{x(x-3)} = \frac{2x^2-18}{2x(x-3)} = \frac{x^2-9}{x(x-3)} =$
$= \frac{(x-3)(x+3)}{x(x-3)} = \frac{x+3}{x}$

б)
$\frac{a+2}{a(2-a)} + \frac{a}{(a-2)(a+2)} = \frac{(-a-2)(a+2)+a^2}{a(a-2)(a+2)} = \frac{-2(a-2)}{a(a-2)(a+2)} = -\frac{2}{a(a+2)}$

в)
$\frac{4x^2}{x-3} - \frac{2x(x-3)}{(x-3)} = \frac{4x^2-2x^2+6x}{x-3} = \frac{2x^2+6x}{(x-3)} = \frac{2x(x+3)}{x-3}$