Newton's laws of motion — practice question

A railway locomotive with mass $240\,000\text{ kg}$ is pulling a coach of mass $36\,000\text{ kg}$ down a slope whose angle to the horizontal is $\sin^{-1} 0.04$. The locomotive provides a driving force of $450\,000\text{ N}$, while the resistive forces are $120\,000\text{ N}$ on the locomotive and $15\,000\text{ N}$ on the coach. The coupling linking the locomotive and the coach is light, rigid and parallel to the hill.