Answer:
a=1
Explanation:
The answer to this problem is 1. This is the answer because using PEMDAS, you would first have to distribute -3.
So: 9a+ -6a+12=15
Combine like terms:
3a+12=15
Subtract 12 on each side. 3a= 3
Divide 3 on each side.
a=1
Hope this helps!! :D