-21=3u-6

Solution for -21=3u-6 equation:

Simplifying
-21 = 3u + -6

Reorder the terms:
-21 = -6 + 3u

Solving
-21 = -6 + 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.
-21 + -3u = -6 + 3u + -3u

Combine like terms: 3u + -3u = 0
-21 + -3u = -6 + 0
-21 + -3u = -6

Add '21' to each side of the equation.
-21 + 21 + -3u = -6 + 21

Combine like terms: -21 + 21 = 0
0 + -3u = -6 + 21
-3u = -6 + 21

Combine like terms: -6 + 21 = 15
-3u = 15

Divide each side by '-3'.
u = -5

Simplifying
u = -5