Simplifying
3x + -8 = 31
Reorder the terms:
-8 + 3x = 31
Solving
-8 + 3x = 31
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '8' to each side of the equation.
-8 + 8 + 3x = 31 + 8
Combine like terms: -8 + 8 = 0
0 + 3x = 31 + 8
3x = 31 + 8
Combine like terms: 31 + 8 = 39
3x = 39
Divide each side by '3'.
x = 13
Simplifying
x = 13