First you need to get rid of the denominator. I like to remember that being the first step because it’s ugly. Nobody likes working with fractions. So get rid of it.
To do this, multiply both sides by the denominator. For the left hand side, that will just get rid of it.
This gives:
4x = (6 x 12)
4x = 72
If you’re solving this for x, then you need your answer to have “x = [answer]”, but right now you have 4x. To get x on its own, you must divide both sides by the 4.
x = (72/4)
x = 18
So your answer is 18.