a) (3x+4)(4x-3) - (2x+5) (6x-7)=5;

б) (x-2) (×+2) = 3(x+4) -2x (x+5);

A) Expanding the brackets, we get:

12x^2 - 9x + 16x - 12 - 12x^2 - 35x + 42 = 5

Simplifying and solving for x, we get:

-28x + 30 = 0

x = 15/14

b) Expanding the brackets, we get:

x^2 - 2x + 2x - 4 = 3x + 12 - 2x^2 - 10x

Simplifying and solving for x, we get:

3x^2 - 6x - 2x^2 + 8x + 14 = 0

x^2 + 2x - 7 = 0

Using the quadratic formula, we get:

x = (-2 ± sqrt(2^2 - 4*1*(-7))) / (2*1)

x = (-2 ± sqrt(32)) / 2

x = -1 ± 2sqrt(2)