A passenger on a bus walks towards the back of the bus at 3.0 km/h relative to the bus, while the bus travels south at 15 km/h.
What is the passenger's velocity relative to the road?
A.
18 km/h north
B.
18 km/h south
C.
15 km/h south
D.
12 km/h north
E.
12 km/h south
