How many more swimmers signed up for the first session at oak pool that the first session at park pool?
763 swimmers signed up for the first session at oak pool
314 swimmers signed up for the first session at park pool
763 is close to 750, and 314 is close to 300, therefore the estimate is: 750 - 300 = 450
The actual answer: 763 - 314 = 449
The answer is reasonable because it is very close to the estimate.