An airplane flew at an average rate of 600 miles per hour from Tokyo to Seattle. Because of a strong headwind, the average rate of the return trip was only 480 mph. The round trip took 18 hours.

A table showing Rate in miles per hour, Time in hours, and Distance in miles. The first row shows Trip to Seattle, and has 600, t and 600 t. The second row shows Trip to Tokyo, and has 480, 18 minus t, and 480 left-parenthesis 18 minus t right-parenthesis.
Which equation can be used to determine the time for each leg?

600t = 480t
600t = 18 – t
600t = 480 – t
600t = 480(18 – t)