
We want to isolate "m" on one side of the equation and have a number on the other side. Let's start by subtracting both sides by 5m


Now, let's subtract both sides by 11


We now have the value of m.
The next thing I'm going to do is a bit tedious, but you typically want to have the variable on the left side of the equation in the field of math. It's a good habit to develop now.

Thus, the answer is choice 3, -18. Let me know if you need any clarifications, thanks!
~ Padoru