To solve this equation, combine like terms on the left side:

3x - 1/2x = 13
(3 - 1/2)x = 13
(6/2 - 1/2)x = 13
(5/2)x = 13

Now, isolate x by dividing both sides by 5/2:

x = 13 / (5/2)
x = 13 * 2/5
x = 26/5
x = 5.2

Therefore, the solution to the equation is x = 5.2.