3(x-3)+x=-21

Solution for 3(x-3)+x=-21 equation:

Simplifying
3(x + -3) + x = -21

Reorder the terms:
3(-3 + x) + x = -21
(-3 * 3 + x * 3) + x = -21
(-9 + 3x) + x = -21

Combine like terms: 3x + x = 4x
-9 + 4x = -21

Solving
-9 + 4x = -21

Solving for variable 'x'.

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

Add '9' to each side of the equation.
-9 + 9 + 4x = -21 + 9

Combine like terms: -9 + 9 = 0
0 + 4x = -21 + 9
4x = -21 + 9

Combine like terms: -21 + 9 = -12
4x = -12

Divide each side by '4'.
x = -3

Simplifying
x = -3