Piecewise functions

Question

Grace wants to go to the mall which is 20 miles east of her house and on the same road. she leaves her house at 3 o’clock and drives 30 mph for six minutes. she is then stopped at a railroad crossing for two minutes. she drives for another three minutes at 40 mph when she realizes she left her wallet at home. Grace makes a U-turn and travels back home but a constant rate in 10 minutes. how fast was great driving during the last 10 minutes of her trip ?

Answer 1

30 miles/hour * 1 hour/60 minutes * 6 minutes = 3 miles

40 miles/hour * 1 hour/60 minutes * 3 minutes = 2 miles

5 miles/10 minutes * 60 minutes/hour = 30 mph