Denise has 6 hours to spend training for an upcoming race. She completes her training by running full speed the distance of the
race and walking back the same distance to cool down. If she runs at a speed of 7mph and walks back at a speed of 3mph, how long should she plan to spend walking back?
To solve this problem,you need to use the formula d = rd (distance = rates x time)She runs at a speed of 7 mph and walks at a speed of 3 mph. Her distance running is d = 7trwhere tr is the time she spends running Her distance walking isd = 3twwhere tw is the time she spends walking The distances are the same so7tr = 3tw We also know that the total time is 4 hourstr + tw = 4tr = 4-tw Substitute this value of tr in the first equation7tr = 3tw7(4-tw) = 3tw28-7tw = 3tw28 = 10tw2.8 = tw Denise will spend 2.8 hours (2 hours, 48 minutes) walking back and 1.2 hours (1 hour, 12 minutes running.
