2*(x+3)+4x=21

Solution for 2*(x+3)+4x=21 equation:

Simplifying
2(x + 3) + 4x = 21

Reorder the terms:
2(3 + x) + 4x = 21
(3 * 2 + x * 2) + 4x = 21
(6 + 2x) + 4x = 21

Combine like terms: 2x + 4x = 6x
6 + 6x = 21

Solving
6 + 6x = 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 + 6x = 21 + -6

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

Combine like terms: 21 + -6 = 15
6x = 15

Divide each side by '6'.
x = 2.5

Simplifying
x = 2.5