It is 165 miles from Dhaka to Chittagong. If a bus takes 1.5 hrs to travel the first 65 miles, how long must the bus take to ...

It is 165 miles from Dhaka to Chittagong. If a bus takes 1.5 hrs to travel the first 65 miles, how long must the bus take to travel the final 100 miles in order to average 50 miles/hr during the entire trip?