Am I correct in my answer or am I off the mark?

If a round-trip and took half the amount of time on the return trip as on the front end of the trip, what would be the relationship between the average rates on each leg of the trip? Using a complete sentence, explain how you arrived at this conclusion.

Student’s answer: 

The average rate of the return trip only took half the time of the

  average rate of the front end of the trip;

  which means, the average rate of the second leg of the trip

  was doubled coming back since it took half the time.

The relationship would be that the average rates are both added together and divided into

the whole trip or both legs of the trip in order to get the average speed of of both legs

combined.

Average Rate = 2d / d / r1  + d / r2 

Is this the right answer?