A Man travelled a distance of 61 km in 9 hours. He travelled partly on foot at 4 km/hr and partly on bicycle at 9 km/hr. What is the distance travelled on foot?
A. 12 km
B. 14 km
C. 16 km
D. 18 km
A. 12 km
B. 14 km
C. 16 km
D. 18 km