Question

Sasha drove from her house to the grocery store in 20 minutes. Her return trip took 15 minutes. If the store is 7 miles from her house, what was Sasha's average speed for the round trip, in miles per hour?

Answer 1

distance = rate * time
7 miles = rate * 20 minutes
7/20 = 20r/20
r = 0.35 mph

Answer 2

Total time = 35 minutes
Total distance = 14 miles

I would set this up as a proportion

14/35 = x/60 (60 minutes in an hour)
Now cross multiply and solve.
35x = 840
840/35 = 24 mph