You have to use the distance formula:
R x T = D (Rate x Time = Distance)
Fill in the information you know:
45 x T = 8.1 (divide both sides by 45 to get T by itself)
T = 8.1/45
T = .18 hours
(which is 60 x .18 = 10.8minutes)
58.285714286 minutes you drive 68 miles 60 minutes you drive 70 miles
8 minutes.
15 minutes.
18 minutes.
22.8 minutes.
25 minutes
26.6666 minutes
500 miles at 1000mph = 30 minutes.
It would take 12 minutes to drive 20 miles at 100 mph.
It would take about 46 minutes to drive 50 miles.
Four minutes at 60 mph
30 minutes