Answer: a) 70 mph
b) 80 mph
Explanation:
Given that Kayleen left home at noon and drove to boston.she got there at 4:00. Then time spent will be 4 hours . Noon means 12pm
Distance covered = 280 miles kayleens average speed will be
Speed = distance/time
Speed = 280/4 = 70 mph
Given that Elijah was already 40 miles closer than Kayleen was when she started
Distance covered by Elijah will be
Distance = 40 + 280 = 320
Time = 4 hours
Speed = 320/4 = 80 mph