Distribute the 3:
9 - ((3*-4) + 3*3x) + 12x
Multiplying it out:
9 - (-12 + 9x) + 12x
Distribute the negative:
9 + 12 - 9x + 12x
Combine like terms:
3x + 21.
Distribute the 3:
9 - ((3*-4) + 3*3x) + 12x
Multiplying it out:
9 - (-12 + 9x) + 12x
Distribute the negative:
9 + 12 - 9x + 12x
Combine like terms:
3x + 21.