As an automobile moves along the road, the vertical displacements at the tires act as the motion

Question:

As an automobile moves along the road, the vertical displacements at the tires act as the motion excitation to the automobile suspension system [16]. Figure

FIGURE AP8.3 Auto suspension system model.
AP8.3 is a schematic diagram of a simplified automobile suspension system, for which we assume the input is sinusoidal. Determine the transfer function X(s)/R(s), and sketch the Bode diagram when M = 1 kg, b = 4 N s/m, and k = 18 N/m.