Ariver current has a velocity of 10 km/h related to the shore in a boat moves in the same direction as a current of 10 km/h related to the ripper how can the velocity of the boat related to the shore be calculated

Relative velocity of the boat with respect to shore is 20 km/h.

Explanation;

Relative velocity of the river with respect to shore,V = 10 km/h

Velocity of the shore = 0 km/h

Relative velocity of the river with respect to shore:

Velocity of the river = 10 km/h

Velocity of the boat =   = ?

Relative velocity of the boat with respect to river ,V'= 10 km/h

Velocity of the boat = 20 km/h

Relative velocity of the boat with respect to shore, V":

Relative velocity of the boat with respect to shore is 20 km/h.