need help with this differential equations problem

EXAMPLE: A damped mass-spring system has a mass of m = 2 kg, a spring with constant k = 20 N/m and variable damping y 2 0. 1. In the undamped case (y = 0), identify the frequency and period of the resulting oscillation. 2. In the damped case (7 > 0), identify a range of y for which the response of the system is a damped oscillator. 3. In the case of y = 4 N/(m/s), find the solution of the system corresponding to the initial conditions x(0) = 0.5, x'(0) = 0.25