A man covers half pan of a certain distance at 35 km/hr. He covers 40 percent of remaining distance at the speed of 8 km/hr and covers rest of the distance at the speed of 18 km/hr. What is his average speed for the entire journey?

A

920/47 km/hr

B

680/47 km/hr

C

840/47 km/hr

D

760/47 km/hr