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?



z(y – x)
--
x + y


z(x – y)
--
x + y


z(x + y)
--
y – x


xy(x – y)
--
x + y


xy(y – x)
--
x + y