Answer:
-13m - 18
Step-by-step explanation:
(3m - 9) -- (-10m - 9 )
Subtract the 3m to the -10m, and add the 9's together.
the answer is 13m
remove parenthesis : 3m – 9 + 10m – 9
simplify : 3m - 9 +10 +9 = 13m
