Answer:
6f + 2
Explanation:
The 9 and the - 7 are "like terms"
They are both constants. That is, they don't have a variable. The terms will be considered "like terms" if they have the same variables to the same power.
So we can combine 9 and - 7.
9 + - 7 is 2.
9 + 6f - 7
= 6f + 9 - 7
= 6f + 2