Probability — practice question

A particle $P$ with mass $0.4\,\mathrm{kg}$ starts from rest at the top of a smooth plane that is tilted at $30^\circ$ to the horizontal. As $P$ moves down the slope, its motion is resisted by a force of magnitude $0.6x\,\mathrm{N}$, where $x\,\mathrm{m}$ denotes the distance $P$ has moved down the slope. Before it reaches the bottom of the slope, $P$ comes to rest.