Answer:
n = 6cm
Step-by-step explanation:
L × W = Area
6(2n + 1) = 78
12n + 6 = 78 Distributive
-6 = -6 Subtract -6 from both sides
12n = 72 Addition
[tex]\frac{12n}{12} = \frac{72}{12}[/tex] Divide each side by 12
