I assume that one of the two "m"s in the given is actually an n, to which I can substitute n = 8.
If this is (1/2)m -(3/4)n = 16:
Then (1/2)m - (3/4)(8) = 16
(1/2)m = 22
m = 44
But if this is (1/2)n -(3/4)m = 16:
Then (1/2)(8) - (3/4)m = 16
4 - (3/4)m = 16
(3/4)m = -12
m = -16