21-3n=2(n+3)

Solution for 21-3n=2(n+3) equation:

Simplifying
21 + -3n = 2(n + 3)

Reorder the terms:
21 + -3n = 2(3 + n)
21 + -3n = (3 * 2 + n * 2)
21 + -3n = (6 + 2n)

Solving
21 + -3n = 6 + 2n

Solving for variable 'n'.

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

Add '-2n' to each side of the equation.
21 + -3n + -2n = 6 + 2n + -2n

Combine like terms: -3n + -2n = -5n
21 + -5n = 6 + 2n + -2n

Combine like terms: 2n + -2n = 0
21 + -5n = 6 + 0
21 + -5n = 6

Add '-21' to each side of the equation.
21 + -21 + -5n = 6 + -21

Combine like terms: 21 + -21 = 0
0 + -5n = 6 + -21
-5n = 6 + -21

Combine like terms: 6 + -21 = -15
-5n = -15

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

Simplifying
n = 3