Isolate the m. Note the equal sign, what you do to one side, you do to the other. First, multiply 2 to both sides
2(1/2m) = 2(12 - m)
m = 2(12 - m)
Distribute 2 to all terms within the parenthesis
m = 24 - 2m
Isolate the m. Add 2m to both sides
m (+2m) = 24 - 2m (+2m)
3m = 24
Isolate the m. Divide 3 to both sides
3m/3 = 24/3
m = 24/3
m = 8
8 should be your answer, or none of the above.
hope this helps