Answer:
According to Newton's third law of motion, every action has an equal and opposite reaction. When Aleksandyr stands on the floor, he exerts a downward force on the floor due to his weight. In response, the floor exerts an equal and opposite force on Aleksandyr, known as the normal force.
Since Aleksandyr weighs 200N, the magnitude of the normal force exerted by the floor on Aleksandyr is also 200N. Therefore, the net force on the floor is 200N in the upward direction, balancing the downward force exerted by Aleksandyr.