125 - (2x - 3)^3 = 5^3 - (2x - 3)^3
125 - (2x - 3)^3 = (5 - (2x - 3))(25 + 5(2x - 3) + (2x - 3)^2)
125 - (2x - 3)^3 = (5 - 2x + 3)(25 + 10x - 15 + 4x^2 - 12x + 9)
125 - (2x - 3)^3 = (8 - 2x)(4x^2 - 2x - 6)
125 - (2x - 3)^3 = 84x^2 - 82x - 86 - 2x4x^2 + 2x2x + 2x6 - 4x^26 + 2x6 + 6*6
125 - (2x - 3)^3 = 32x^2 - 16x - 48 - 8x^3 + 4x + 12 - 24x^2 + 12x + 36
125 - (2x - 3)^3 = -8x^3 + 8x^2 - 2x - 40