Answer:
n=3
Explanation:
Simplifying
8n + 12 + -5n = 21
Reorder the terms:
12 + 8n + -5n = 21
Combine like terms: 8n + -5n = 3n
12 + 3n = 21
Solving
12 + 3n = 21
Solving for variable 'n'.
Move all terms containing n to the left, all other terms to the right.
Add '-12' to each side of the equation.
12 + -12 + 3n = 21 + -12
Combine like terms: 12 + -12 = 0
0 + 3n = 21 + -12
3n = 21 + -12
Combine like terms: 21 + -12 = 9
3n = 9
Divide each side by '3'.
n = 3
Simplifying
n = 3