Помогите срочно надо дам корону!!!к

Решите задачу:

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

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

$\frac{x + y}{y} \times \frac{ {x}^{2} }{ax + ay} = \frac{x + y}{y} \times \frac{ {x}^{2} }{a(x + y)} = \frac{ {x}^{2} }{ ay}$

$\frac{ {a }^{2} - {b}^{2} }{b} \div \frac{ {a}^{2} + ab }{b} = \frac{(a - b)(a + b)}{b} \times \frac{b}{a(a + b)} = \frac{a - b}{a}$

$\frac{15b}{3 - b} + \frac{8b}{b {}^{2} - 9} \times \frac{7b + 21}{4} = \frac{15b}{3 - b} + \frac{8b}{(b - 3)(b + 3)} \times \frac{7(b + 3)}{4} = \frac{15b}{3 - b} + \frac{14b}{b - 3} = \frac{ 15b {}^{2} - 45b - 14b {}^{2} + 42b }{ - (b - 3)(b - 3)} = \frac{b {}^{2} - 3b}{ - (b - 3)(b - 3)} = \frac{b(b - 3)}{- (b - 3)(b - 3)} = \frac{b}{3 - b}$

$\frac{2a - 2c + ax - cx}{ {x}^{2} - 4} = \frac{2(a - c) + x(a - c)}{(x - 2)(x + 2)} = \frac{(x + 2)(a - c)}{(x - 2)(x + 2)} = \frac{a - c}{x - 2} = \frac{6.7 - 3.5}{1.9 - 2} = \frac{1.4}{ - 0.1} = - 14$