This puzzle is a variation of a puzzle I had posted very early (amongst my first 10 posts). It is very simple, and intended for children. Thanks to Suman Saraf for contributing this one.
Alice and Bob go into their local donut shop. Alice buys five donuts, and Bob buys three. As they are leaving, they meet Charlie and decide to cut-up, and share, all eight donuts equally between the three of them. After the feast, Charlie reaches into his pocket and discovers he has $0.80 in coins. Even though he knows that this amount of money is less than his share of the donuts eaten, he wants to compensate, as fairly as possible, Alice and Bob.
Question: How much of the money should he give Alice, and how much should he give Bob?
(All the donuts are same price, everyone eats the same amount, and ‘fair’ means repayment of Alice and Bob equal percentages of their own individual outlays)