So what you want to do is move all the variables to one side and numbers to the other.
x-3 = 3x + 7
So first move all the variables to one side:
x - 3x - 3 = 7
Then the numbers.
x- 3x = 7 + 3
Simplify
-2x = 10
Then divide both sides by -2.
-2x = 10
/-2 /-2
x = -5
