Question

Why displacement cannot be added or substracted like scalar quantities?

Answer 1

Because displacement is a vector quantity. It not only has a magnitude but alao a direction.Displacement can be positive or negetive depending on the direction of motion of the body. So it cannot be added or subtracted like scaler quantities.

Answer 2

it is vector quantity, it can be added or subtracted by following vector rules like parallelogram law ,triangle law etc