In this problem it is asking how many gallons the pool holds. It gives you a method of exchange from cubic feet to this however, so in order to solve for this, we first have to solve for how many cubic feet is in the swimming pool, or how much volume the swimming pool has. The formula for the volume of a rectangle is Length*Width*Depth=Volume. Plugging in what we have we get 30*20*6=Volume, or Volume = 3600. As there are 7.5 gallons of water in each cubic foot, we simply multiply 7.5 times 3600 to get the answer. This is 27000.
