Answer: x = 3
Step-by-step explanation:Simplifying 
12 + 5x = 18 + 3x 
 
Solving 
12 + 5x = 18 + 3x 
 
Solving for variable 'x'. 
 
Move all terms containing x to the left, all other terms to the right. 
 
Add '-3x' to each side of the equation. 
12 + 5x + -3x = 18 + 3x + -3x 
 
Combine like terms: 5x + -3x = 2x 
12 + 2x = 18 + 3x + -3x 
 
Combine like terms: 3x + -3x = 0 
12 + 2x = 18 + 0 
12 + 2x = 18 
 
Add '-12' to each side of the equation. 
12 + -12 + 2x = 18 + -12 
 
Combine like terms: 12 + -12 = 0 
0 + 2x = 18 + -12 
2x = 18 + -12 
 
Combine like terms: 18 + -12 = 6 
2x = 6 
Divide each side by '2'. 
x = 3 
 
Simplifying 
x = 3