Question 1173681

Fred took 7 h to drive from Cheyenne to Boothill, a total distance of 485. He drove most of the way at 80 km/h, but was slowed to 30 km/h for a time by a dust storm during the trip. How many hours did he spend driving through the dust storm?
<pre>Let time spent driving through sand storm, be T
Then time NOT spent in a sand storm = 7 - T
We then get the following DISTANCE equation: 30T + 80(7 - T) = 485
30T + 560 - 80T = 485
30T - 80T = 485 - 560
- 50T = - 75
Time spent driving in sand storm, or {{{highlight_green(matrix(1,6, T, "=", (- 75)/(- 50), "=", 1.5, hours))}}}