Answer:
3.
Step-by-step explanation:
3(n + 4) = 21
3n + 12 = 21
3n = 21 - 12 = 9
n = 3.
n = 3
Given
3(n + 4) = 21 ( divide both sides by 3 )
n + 4 = 7 ( subtract 4 from both sides )