Two towns P and Q are 400 km apart. A bus left P for Q. It stopped at Q for one hour and then started the return journey to P. One hour after the departure of the bus from P, a trailer also heading for Q left P. The trailer met the returning bus% of the way from P to Q. They met t hours after the departure of the bus from P. (a) Express the average speed of the trailer in terms of 1 (b) Find the ratio of the speed of the bus to that of the trailer. (2 marks)