When you sit on your chair, you exert a downward force on the chair which we call an action force. According to Newton's 3rd law, what is the reaction force?

This is the answer: body 1 + engine 2

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.