In the 80s in Brooklyn ny 2 of my friends and I whent to bar , we ate, we drink and shoot pool. When done we asked the waitress for the bill. It was $30 we gave her the money , when she gave the cash to the owner he said i am going to charge only $25 because he knew my friend so she came back with five $1 bills , we took one each and let her keep the other $2. So if we got $1 back each that means we only spent $9 each, thats 3x9 thats $27 and The $2 we let her keep is 29. One dollar is on the limbo. CAN YOU DO THE MATH ?