Here is the solution to the given problem above. Given the the amount of water in a pool is decreasing 5/8 gallon every hour. And what would be the change in the number of gallons after 3/4 hour. So what we are going to do is just to multiply 5/8 by 3/4. And the result would be 15/32. The total change in the number of gallons of water in the pool after 3/4 hour would be 15/32 gallons.