Answer:
M = 60
Step-by-step explanation:
You are doing the opposite to each side to simplify the inequality so on one side it is the variable in your case, it is m and the other side is your number. You are going to add 138 to both sides and then you get your answer.
-78 ≤ M - 138
-78 + 138 ≤ M - 138 +138
60 ≤ M
=
M ≥ 60
