Phil is making a 40-kilometer canoe trip. If he travels at 30 kilometers per hour for the first 10 kilometers, and then at 15 kilometers per hour for the rest of the trip, how many minutes more will it take him then if he travels the entire trip at 20 kilometers per hour?

Answer 1

total time at 20 km/h = 40 km/ 20 km/h
= 2 hours

time of 1st part = 10/30 = 1/3 hr = 20 minutes
time of 2nd part = 30/15 = 2hours
for a total of 2:20 hrs

so it would take him 20 minutes extra