Question

-1/3m - 7 = 5

Answer 1

-1/3m - 7 = 5
-1/3m = 12
m = -36

Answer 2

You first want to add 7 to both sides. This gives you 12=-1/3 m
Now, you want to divide out the -1/3 and you do that by multiplying by the reciprocal...
12*-3=-36
m=-36