Answer:
15x - 2
Explanation:
Since there is an addition sign in between the parentheses, just ignore the parentheses all together. You can't combine anything inside the parentheses anyways.
New expression:
12x + 5 + 3x - 7
Combine like terms.
12x + 3x = 15x 5 - 7 = -2
Answer:
15x - 2