-42=-3(u+4)

Solution for -42=-3(u+4) equation:

Simplifying
-42 = -3(u + 4)

Reorder the terms:
-42 = -3(4 + u)
-42 = (4 * -3 + u * -3)
-42 = (-12 + -3u)

Solving
-42 = -12 + -3u

Solving for variable 'u'.

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

Add '3u' to each side of the equation.
-42 + 3u = -12 + -3u + 3u

Combine like terms: -3u + 3u = 0
-42 + 3u = -12 + 0
-42 + 3u = -12

Add '42' to each side of the equation.
-42 + 42 + 3u = -12 + 42

Combine like terms: -42 + 42 = 0
0 + 3u = -12 + 42
3u = -12 + 42

Combine like terms: -12 + 42 = 30
3u = 30

Divide each side by '3'.
u = 10

Simplifying
u = 10