Помогитееее надо прям какой сможете

2.
$\frac{3}{a} + \frac{a-3}{a+5} = \frac{3(a+5)+a(a-3)}{a(a+5)} = \frac{3a+15+a^2-3a}{a(a+5)} = \frac{a^2+15}{a^2+5a} \\ \\ \frac{2x^2}{x^2-4} - \frac{2x}{x+2} = \frac{2x^2 - 2x(x-2)}{(x-2)(x+2)} = \frac{2x^2-2x^2+4x}{(x-2)(x+2)} = \frac{4x}{x^2-4}$

3.
$\frac{y^2 - 6y + 9}{y^2 - 9} : \frac{10y - 30}{y^2+3y} = \frac{(y-3)^2}{(y-3)(y+3)} : \frac{10(y-3)}{y(y+3)} = \frac{y-3}{y+3} : \frac{10(y-3)}{y(y+3)} = \\ \\ = \frac{y-3}{y+3} * \frac{y(y+3)}{10(y-3)} = \frac{y}{10} = \frac{1}{10}*y = 0.1y \\ \\ y = 70 \\ 0.1 * 70 = 7 \\ \\$

4.
x/y = a
x = ay

y/z = 1/a
1*z = ay
z=ay

x/z = ay/ay
x/z = 1