Answer:
Total Area = 2 × 6 + 4 × 6 = 72 + 18 = 90 in^2
Step-by-step explanation:
We are given both the total area (36) and total perimeter of the sides (90).
72 + _ = 90
90 - 72 = 18
2 × _ + 4 × _ = 36
2 × 6 + 4 × 6
12 + 24 = 36
