Answer:
5. 11.25 mi/hr
6. 24 hours
Step-by-step explanation:
5. The return trip at 9 mph took 5 hours. So the distance is 45 miles.
The total distance traveled is therefore 90 miles, and the total time is 3 + 5 = 8 hours.
The average speed is distance divided by time, or (90 mi) / (8 hr) = 11.25 mi/hr
6. If t is the time it takes driving there, then t−4 is the time it takes to drive back.
Distance = speed × time, so the forward trip is 25t miles, and the return trip is 30(t−4) miles. These distance are equal, so:
25t = 30(t−4)
25t = 30t − 120
120 = 5t
t = 24
