Answer:
11m
Explanation:
9m + 3m - m = ?
just look at it without the variables: m
9 + 3 - 1 = ?
The reason there is a 1 before the m is because there is always atleast a 1 before a variable. 1 x m = m, but 0 x m = 0. so '1'.
ok so now lets solve
9 + 3 - 1
12 - 1
11
so the answer is 11, add the variables back
9m + 3m - m
12m - m
11m