Решение:

а) 10х - 2(4x-5) = 2x + 10

10x - 8x + 10 = 2x + 10

2x + 10 = 2x + 10

2x - 2x = 10 - 10

0 = 0

x - любое число

б) $$\frac{2}{5x-2}$$ = $$\frac{5}{7}$$

2 * 7 = 5 * (5x - 2)

14 = 25x - 10

25x = 14 + 10

25x = 24

x = $$\frac{24}{25}$$

x = 0,96