The answer you are looking for is X = 17.
First, you would combine like terms (x and 3x) to get 4x. The equation would now say 4x + 4 = 72.
Next, you subtract 4 from both sides. Doing this cancels out the 4 on the left side of the equation, and leaves 68 on the right side.
Finally, you divide both sides by 4 (in order to get "x" by itself). Thus getting an answer of X = 17.
I hope this helps!