Calculating Force on Wheaties from Cheerios: 28 N

[goaliejoe35]

Homework Statement
A box of Cheerios (mass mC = 1.2 kg) and a box of Wheaties (mass mw = 3.7 kg) are accelerated across a horizontal surface by a horizontal force F applied to the Cheerios box. The magnitude of the frictional force on the Cheerios box is 1.6 N, and the magnitude of the frictional force on the Wheaties box is 6.3 N. If the magnitude of F is 28 N, what is the magnitude of the force on the Wheaties box from the Cheerios box?

The attempt at a solution

I need some help setting this up. Shouldn't the magnitudes of the forces applied by both boxes equal each other?

 

[goaliejoe35]

I was able to solve it.