To find the tip you have to change the percent into a fraction first. Since percent is out of a 100, 25% is 25/100 or 1/4. Multiplying 1/4 by 520 you get 130, which is how much the coach will tip.
Explanation: 100-44 is 56, so 280 is equal to 56% of the trip. 280/56 is equal to 5. Therefore 5 is 1%, so if we multiply the 5 x 100 there we go, that's 100% of the trip. Not how your teacher told you to do it, but its the right answer.