36=42-u

Solution for 36=42-u equation:

Simplifying
36 = 42 + -1u

Solving
36 = 42 + -1u

Solving for variable 'u'.

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

Add 'u' to each side of the equation.
36 + u = 42 + -1u + u

Combine like terms: -1u + u = 0
36 + u = 42 + 0
36 + u = 42

Add '-36' to each side of the equation.
36 + -36 + u = 42 + -36

Combine like terms: 36 + -36 = 0
0 + u = 42 + -36
u = 42 + -36

Combine like terms: 42 + -36 = 6
u = 6

Simplifying
u = 6