Answer:
Subtract
Explanation:
You should subtract since the equation says to add.
You basically do the opposite of what it says.
For example, if it was m - 9 = 45 you would add 9 on both sides, but in this case, you would subtract since its m + 9 = 45
m + 9 = 45
subtract nine by 9 and 45:
m = 36
36 + 9 = 45