Три задания решите пожалуйста)))

$\frac{x+8}{x-9} -3 = 0$
$\frac{x+8}{x-9} = 3$
x+8 = 3(x-9)
x+8 = 3x-27
27+8 = 3x-x
35 = 2x
x = 17,5

$\frac{5-x}{x+12} = \frac{-16}{x-15}$
(5-x)*(x-15) = (x+12)*(-16)
5x - 75 - x² + 15x = -16x - 192
x² - 4x - 117 = 0
D = b² - 4ac = 16 + 468 = 484
x = $\frac{b^{2} (+-) \sqrt{D} }{2a} = \frac{16 (+-) 22 }{2} = 6 (+-) 11$
x₁ = 6 - 11 = -5
x₂ = 6 + 11 = 17