how many hours did it take him to drive home?

Question

john walked 27 miles to the car dealer.  Because his car was 9 times faster than he was, john drove home in 4 hours less than it took him to walk to the car dealer.  How many hours did it take him to drive home?

Answer 1

d = rt

27 = rt (walking)

27 = 9r(t - 4) (driving)

3 = rt - 4r

3 = 27 - 4r

4r = 24

r = 6

 

27 = 6t

t = 4.5

 

4.5 - 4 = 0.5 hours = 30 minutes