Simplifying x + 2x = 5 + 10 Combine like terms: x + 2x = 3x 3x = 5 + 10 Combine like terms: 5 + 10 = 15 3x = 15 Solving 3x = 15 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Divide each side by '3'. x = 5 Simplifying x = 5