Subtract (2-4x^9+3x^3)-(7x+x^3-6+12x^4) and simplify

(2-4x^9+3x^3)-(7x+x^3-6+12x^4)

= 2 - 4x^9 + 3x^3 - 7x - x^3 + 6 - 12x^4
= -4x^9 + 12x^4 + 2x^3 - 7x + 8