d- distance
s- speed
t- time
c. d= st
d= 12 km per hour * 6 hours
d= 72 km
3a. t=d/s
t= 20m/ (5m/s)
t= 4s
b. t= d/s
t= 45m/ (9m/s)
t= 5s
c. t= d/s
t= 60miles/ (15 miles/hour)
t= 4h
