х+8/5х+7=х+8/7х+5;

(х+8)(7х+5)=(х+8)(5х+7);

7x²+56х+5х+40=5х²+40х+7х+56;

2х²+14х-16=0

Д= 196+128=324

х=1

х=-8

(наверное, так)

x+8/5x+7 = x+8/7x+5

(7x + 5) * (x + 8) = (5x + 7) * (x + 8)

7x² + 56x + 5x + 40 = 5x² + 40x + 7x + 56

7x² + 61x + 40 = 5x² + 47x + 56

2x² + 14x - 16 = 0

x² + 7x - 8 = 0

D= 7² - 4*(-8) = 49 + 32 = √81 = 9

x₁ = (-7+9)/2 = 2/2 = 1  

x₂ = (-7 - 9)/2 = -16/2= -8

ответ: -8 ; 1