The answer to your question is 'The Changs paid the correct amount for their purchases'. I apologize for being late, but this answer may help others later.
So the questions ask to write an equations that shows how much money will be donated and then solve. So let Y be the amount of money and X will be the number of people attending. So the equation would be y=(10-5.5)X so the answer would be Y=2250. I hope you are satisfied with my answer and feel free to ask for more
I believe the answer is the ship is traveling at 21.25 MPH, started 10.5 miles from lighthouse and after 11 hours will be 244.25 miles from the lighthouse.