Answer:
$8421.60
Explanation:
First, we need to convert the dimensions of the deck from yards to square yards, since the cost is given per square yard.
The area of the deck is the product of its length and width:
8 yards * 12 yards = 96 square yards
So, the cost to build the deck is:
$87.85/square yard * 96 square yards = $8421.60
Therefore, it cost $8421.60 to build the deck.