A person covered a certain distance by bus at the rate of 40 kmph and walked back to the initial point at the rate of 6 kmph. The whole journey took 13 hours and 48 minutes. What distance did he walk?
a) 60km
b) 64 km
c) 70km
d) 72km
e) 80 km
a) 60km
b) 64 km
c) 70km
d) 72km
e) 80 km