Make sure you have a common denominator first so it would be
9/16x = 12/16 (you multiply 3/4 by 4/4 to get the bottom to equal 16)
Afterwards, times 16 on each side to get rid of it. Then you get 9x = 12
By dividing 9 on each side to isolate the variable, you would get x = 12/9
Afterwards, simplify it.
x = 4/3
