Two good friends
Andrew and Brian went for a week-long trip together and agreed to share the costs equally. Over the week, each of them paid for various joint expenses such as gasoline and car rental. At the end of the trip, it turned out that Andrew had paid \(A\) dollars and Brian had paid \(B\) dollars, where \(A < B\).
How many dollars must Andrew give to Brian so that they share their costs equally ?