Answer
The weight of the person is not a force exerted on the scale. The weight of the person is the gravitational force pulling down on the person.
Work Step by Step
These three forces are forces acting on the scale:
A contact force from the floor pushes up on the scale.
A contact force due to the person's feet pushes down on the scale.
The weight of the scale is the gravitational force pulling down on the scale.
However, the weight of the person is not a force exerted on the scale. The weight of the person is the gravitational force pulling down on the person.
