1. The problem statement, all variables and given/known data 1) Are F and F' as shown in figure, the action-reaction forces between the two boxes? 2) What is the action and reaction force between the two boxes? 2. Relevant equations 3. The attempt at a solution I think F = 28N and F' = - 28 N Simply adding the action- reaction forces for each case of 4 N and 24 N external forces.