6(x+1)+3(x-4)=21

Solution for 6(x+1)+3(x-4)=21 equation:

Simplifying
6(x + 1) + 3(x + -4) = 21

Reorder the terms:
6(1 + x) + 3(x + -4) = 21
(1 * 6 + x * 6) + 3(x + -4) = 21
(6 + 6x) + 3(x + -4) = 21

Reorder the terms:
6 + 6x + 3(-4 + x) = 21
6 + 6x + (-4 * 3 + x * 3) = 21
6 + 6x + (-12 + 3x) = 21

Reorder the terms:
6 + -12 + 6x + 3x = 21

Combine like terms: 6 + -12 = -6
-6 + 6x + 3x = 21

Combine like terms: 6x + 3x = 9x
-6 + 9x = 21

Solving
-6 + 9x = 21

Solving for variable 'x'.

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

Add '6' to each side of the equation.
-6 + 6 + 9x = 21 + 6

Combine like terms: -6 + 6 = 0
0 + 9x = 21 + 6
9x = 21 + 6

Combine like terms: 21 + 6 = 27
9x = 27

Divide each side by '9'.
x = 3

Simplifying
x = 3