Directions: Study the following information carefully and answer the questions given below. 

Rohit embarks on a 93 km journey using three different vehicles: Tesla, Mercedes, and Ford. The average speed of his entire journey is 93 km/h. For the part of the journey covered by Mercedes and Ford, the average speed is 76.8 km/h. The ratio of the speed of the Tesla to the Mercedes is 8:5, while the speed of the Tesla is 50% more than the speed of the Ford. The difference between the speeds of the Mercedes and the Ford is 5 km/h.

If the speed of the Tesla is reduced by 'p' km/h and the speed of the Mercedes is increased by 'q' km/h such that the speeds of the Tesla and Mercedes become equal, the total time for the journey increases by 3.5 minutes.