Two masses are in contact on a horizontal frictionless surface. A horizontal force is applied to M_1 and a second horizontal force is applied to M_2 in the opposite direction. What is the magnitude of the contact force between the masses?

A 3 kg mass, M_1, and a 10 kg mass, M_2, are in contact on a horizontal frictionless surface. A constant horizontal force 14.3 N in the positive x direction is applied to M_1 and a constant horizontal force 12.2 N in the negative x direction is applied to M_2. The masses stay in contact while they move. Calculate the magnitude of the contact force between the two masses.