120=100-0+x-40

Solution for 120=100-0+x-40 equation:

Simplifying
120 = 100 + 0 + x + -40

Reorder the terms:
120 = 100 + 0 + -40 + x

Combine like terms: 100 + 0 = 100
120 = 100 + -40 + x

Combine like terms: 100 + -40 = 60
120 = 60 + x

Solving
120 = 60 + x

Solving for variable 'x'.

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

Add '-1x' to each side of the equation.
120 + -1x = 60 + x + -1x

Combine like terms: x + -1x = 0
120 + -1x = 60 + 0
120 + -1x = 60

Add '-120' to each side of the equation.
120 + -120 + -1x = 60 + -120

Combine like terms: 120 + -120 = 0
0 + -1x = 60 + -120
-1x = 60 + -120

Combine like terms: 60 + -120 = -60
-1x = -60

Divide each side by '-1'.
x = 60

Simplifying
x = 60