Answer:
7x21
Step-by-step explanation:
First, we need to find the length of the pool. Since it is three times as long as it is wide, it is 21 feet long (7 x 3 = 21). That way we can tell that it is 7x21, with a perimeter of 56 feet, and an area of 147 feet squared.
The answer is C, 488 cm2
192