A hot dog vendor at a soccer game sells one half of his supply of hot dogs during the first half of the game. During intermission, he sells a total of five hot dogs. During the second half, he sells three-eighths of his original supply. He is left with only four hot dogs. How many did he have to start with?

Answer
Five hot dogs (intermission) plus four hot dogs (left over) equals just one-eighth of his original supply, because we know that a total of seven- eighths was sold during the game itself. That means the vendor must have started the soccer game with 9 x 8 = 72 hot dogs.