3nw² + 12x - -nw² – -2x +3x
3nw2 + 12x - -nw2 - -2x + 3x = (3nw2 - -nw2) + (12x - -2x + 3x)
= (3nw2 + nw2) + (12x + 2x + 3x)
= 4nw2 + 17x
