It takes the high-speed train x hours to travel the z miles from Town A to Town B at a constant rate, while it takes the regular train y hours to travel the same distance at a constant rate. If the high-speed train leaves Town A for Town B at the same time that the regular train leaves Town B for Town A, how many more miles will the high-speed train have traveled than the regular train when the two trains pass each other?


a. z(y – x)/x + y


b. z(x – y)/x + y


c. z(x + y)/y – x


d. xy(x – y)/x + y


e. xy(y – x)/x + y