9x²-7(x+4)·(4-x)-(1-4x)²=15

9x^2-7(x+4)*(4-x)-(1-4x)^2=15 16x^2-112-1+8x-16x^2-15=0 16x^2-113+8x-16x^2-15=0 -113+8x-15=0 -128+8x=0 x=128/8 x=16