If Chad drove 168 miles in 2 hours than he drove 84 miles in one hour. If he drove 840 miles than you divide 840 by 84 and you get 10 hours. To check your work you can do 84*10= 840 miles 84=representing the miles per hour and 10=representing the amount of hours he drove.
First we need to find the rate Chad is driving. The rate is equal to distance/time, so we do 168/2, which is 84 mph. Then we have to find the time, which is distance/rate, so that would be 840/84, which is 10 hours.
