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This is a tough rate problem, so rather than try to calculate the solution, you may be better off trying to guesstimate the answer. For instance, it took Vaughn 2 hours to complete the round trip, and he drove more slowly on the way to work than on the return trip. Therefore, he must have spent more time going to work than coming back. So the answer must be more than 60 minutes, and the only possible answer choice that works is Choice (5), 70 minutes.
To calculate the answer mathematically, you could begin by calling the distance either way d. Since Time = Distance/Rate, we can come up with the equation for the time spent traveling and solve for d (keeping our units in hours for now): 
. So 
.
Thus 
, and 
(We'll do what reducing we can and save the final number-crunching for later). Now that we have the distance, we should divide that by the rate (25 m.p.h.) to determine the time (in hours) it took Vaughn to drive to work:
Now we multiply that by 60 to convert the answer into minutes: 
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Video Lessons and 10 Fully Explained Grand Tests
Large number of solved practice MCQ with explanations. Video Lessons and 10 Fully explained Grand/Full Tests.