42=3u+4u

Solution for 42=3u+4u equation:

Simplifying
42 = 3u + 4u

Combine like terms: 3u + 4u = 7u
42 = 7u

Solving
42 = 7u

Solving for variable 'u'.

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

Add '-7u' to each side of the equation.
42 + -7u = 7u + -7u

Combine like terms: 7u + -7u = 0
42 + -7u = 0

Add '-42' to each side of the equation.
42 + -42 + -7u = 0 + -42

Combine like terms: 42 + -42 = 0
0 + -7u = 0 + -42
-7u = 0 + -42

Combine like terms: 0 + -42 = -42
-7u = -42

Divide each side by '-7'.
u = 6

Simplifying
u = 6