Final answer:
The shortest side of the deck is 12 feet. The second side is 15 feet. The third side is 21 feet.
Step-by-step explanation:
Let x be the length of the shortest side of the deck.
The second side is 3 feet longer than the shortest side, so its length is x + 3.
The third side is 3 feet shorter than twice the length of the shortest side, so its length is 2x - 3.
The perimeter of a triangle is the sum of the lengths of its sides. We can set up an equation to find x:
x + (x + 3) + (2x - 3) = 48
Combining like terms, we get 4x = 48, so x = 12.
The shortest side of the deck is 12 feet. The second side is 12 + 3 = 15 feet. The third side is 2(12) - 3 = 21 feet.