Suppose that three equally charged spheres are placed at three corners of rectangle ABCD $($.$).$ The distance from A to B is $11\mathrm{.}4$ cm,$,$ and the distance from B to C is $6\mathrm{.}7$ cm.$.$ Sphere C exerts a force of $38\mathrm{.}7$ N on sphere B$.$ What force does A exert on B?$?$