Judy drove 20 miles from her house to a theater at an average rate of 50 miles per hour. Greg drove from his house to the theater in $$\frac{1}{3}$$ of the time it took Judy to drive to the theater, and they both arrived at the theater at the same time. If Judy left her house at 7:30 p.m., when did Greg leave his house?
答案：D