8. John roller skates 48.5 miles with a constant speed of 12 mph and another 5 miles with a constant speed of 10 mph. How much time in total does he take to travel these distances? 9. A taxi hurries for 3/4 hours with a constant speed of 84 km/h and then for another 2 hours 15 minutes with a constant speed of 96 km/h. What distance did it go? 10. David's airplane trip took 3.8 hours. For onefourth of that time, the airplane ew at a speed of 840 km/h, and for the rest of the time, it ew at a speed of 960 km/h. What distance did David travel