Question

Two people push on a box that has a mass of 10kg, the person on the right has a mass of 86kg and applies a horizontal force of 50N. The person on the left has a mass of 45kg. The coefficient of kinetic friction between the box and the floor is .2, the coefficient of static friction is .4. If the box moves to the left with a constant velocity of 10 m/s, what is the force applied by the person on the left?