21=5n-2(n-3)

Solution for 21=5n-2(n-3) equation:

Simplifying
21 = 5n + -2(n + -3)

Reorder the terms:
21 = 5n + -2(-3 + n)
21 = 5n + (-3 * -2 + n * -2)
21 = 5n + (6 + -2n)

Reorder the terms:
21 = 6 + 5n + -2n

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

Solving
21 = 6 + 3n

Solving for variable 'n'.

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

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

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

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

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

Combine like terms: 6 + -21 = -15
-3n = -15

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

Simplifying
n = 5