(2n+1)3=-21

Solution for (2n+1)3=-21 equation:

Simplifying
(2n + 1) * 3 = -21

Reorder the terms:
(1 + 2n) * 3 = -21

Reorder the terms for easier multiplication:
3(1 + 2n) = -21
(1 * 3 + 2n * 3) = -21
(3 + 6n) = -21

Solving
3 + 6n = -21

Solving for variable 'n'.

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

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

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

Combine like terms: -21 + -3 = -24
6n = -24

Divide each side by '6'.
n = -4

Simplifying
n = -4