how do I solve this?

2. Figure 2 depicts three masses, mj, m2, and my connected by springs. The springs on either end are connected to walls. YOU MAY ASSUME k] = k2 = k3 = k4 and that all the masses are the same. a) (20 points) Find the equations of motion for this system. b) (30 points) Find the normal mode frequencies, @ for this system. c) (10 points) Can you identify what motion the three eigenvectors identify in the system