(6х-7)^2-5*(2х-5)*(2х+5)-2*(4х-15)*(2х-4)=-2

(6х-7)²-5(2х-5)(2х+5)-2(4х-15)(2x-4)= -2
36x²-84x+49-5(4x²-25)-2(8x²-30x-16x+60)+2=0 
36x²-84x+49-20x²+125-16x²+60x+32x-120+2=0
36x²-20x²-16x²-84x+60x+32x+49+125-120+2=0
8x+56=0
8x= -56
x= -7

(6*(-7)-7)²-5(2*(-7)-5)(2*(-7)+5)-2(4*(-7)-15)(2*(-7)-4)= (-42-7)²-5(-14-5)(-14+5)-2(-28-15)(-14-4)= (-49)²-5*(-19)*(-9)-2*(-43)*(-18)=2401-855-1548= -2