The position function for the bus is = 60*t
For the car, since it had a head start of 1.5 hrs, it would have gone 60 miles ahead. So the position function is =40*t+60
for both to be in the same position, and the bus to over take the car, equate the two functions.
60t=40t+60
solving for t=3 hrs
It will take 3 hours.