Hello! :D
Answer:

*The answer should have a positive sign.*
Explanation:
First, you do is switch sides.

Then, you add by 7 from both sides.

Add numbers from left to right.


Multiply by 2 from both sides.

Finally, multiply numbers from left to right.

m=18 is the correct answer.
I hope this helps you!
Have a wonderful day! :)
:D
-Charlie
Thanks!