Алгебра помогите зделать срочно

А)
$\frac{(1 -y)(1 + y)}{2(a + b)( {a}^{2} - ab + {b}^{2} ) } \times \frac{ {a}^{2} - ab + {b}^{2} }{3(1 - y)} = \frac{1 + y}{6(a + b)}$

$\frac{5(a - b)}{(x - y {)}^{2} } \times \frac{x - y}{a - b} = \frac{5}{x - y}$
б)
$\frac{3(a - b)}{5(a + b)} \times \frac{(a + b {)}^{2} }{(b - a)(b + a)} = - \frac{3}{5}$
в)
$\frac{(4 - x {)}^{2} }{y(x + y) } \times \frac{(x - y)(x + y)}{3(4 - x)} = \frac{(4 - x)(x - y)}{3y}$
г)
$\frac{(1 - y)(1 + y)}{2(a + b)( {a}^{2} - ab + {b}^{2} )} \times \frac{( {a}^{2} - ab + {b}^{2}) }{3(1 - y)} = \frac{1 + y}{6(a + b)}$
д)
$\frac{15a}{2b(a + b)} \times ( \frac{a + b } {5a})^{2} = \frac{3(a + b)}{10ab}$
е)
$\frac{(a - 1)(a + 1)}{(x - 1)( {x}^{2} + x + 1 ) } \times \frac{ {x}^{2} + x + 1 }{(a + 1 {)}^{2} } = \frac{a - 1}{(x - 1)(a + 1)}$