123=-42-15x

Solution for 123=-42-15x equation:

Simplifying
123 = -42 + -15x

Solving
123 = -42 + -15x

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '15x' to each side of the equation.
123 + 15x = -42 + -15x + 15x

Combine like terms: -15x + 15x = 0
123 + 15x = -42 + 0
123 + 15x = -42

Add '-123' to each side of the equation.
123 + -123 + 15x = -42 + -123

Combine like terms: 123 + -123 = 0
0 + 15x = -42 + -123
15x = -42 + -123

Combine like terms: -42 + -123 = -165
15x = -165

Divide each side by '15'.
x = -11

Simplifying
x = -11