A river current has a velocity of 5 km/h relative to the shore, and a boat moves in the same direction as the current at 5 km/h relative to the river. How can the velocity of the boat relative to the shore be calculated?
A. by subtracting the river current vector from the boat’s velocity vector
B. by dividing the river current vector by the boat’s velocity vector
C. by multiplying the vectors
D.by adding the vectors
