Ok I know distance equals rate x time but for some reason I cannot get this question set up correctly.

"A family drove to Disneyland at 50mph and returned the same route at 40mph. What is the distance to Disneyland if the total driving time was 7.2 hours."

I know the answer is right in front of my face but it is not clear to me. The answer to this question is great but I must know how to set up an equation with the inputed information. HELP PLEASE!!