Chapter 4.1, Problem 20P

A body of mass $m$ is attached between two springs with spring constants $k_1$ and $k_2$, as shown in Figure $\mathrm{4.1.11.}$ The springs are at their rest length when the system is in the equilibrium state. Assume that the mass slides without friction but the motion is subject to viscous air resistance with coefficient $\gamma$. Find the differential equation satisfied by the displacement $x\left(t\right)$ of the mass from its equilibrium position.