A box of mass m = 3.50 kg is given a push down an inclined plane which makes an angle of 30 degree with the horizontal. The box moves at 2.00 m/s when it is 30.0 cm vertically above the top of the spring, and the coefficient of kinetic friction between the box and the incline is 0.25. If the force constant of the spring is k = 20.0 N/m, find the maximum displacement of the end of the spring.