<PRE><B>Question 736501</B>
mary drove 138 miles one way to visit her mother which took 2 1/2 hours.
 The return trip took 3 1/4 hours due to more traffic.
 what was her average speed for the entire trip
:
Let a = average speed for the whole trip, total distance/total time.
The round trip = 2(138) = 276 mi
total time for the trip: 2.5 + 3.25 = 5.75 hrs

:
a = {{{276/5.75}}}
a = 48 mph 
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