$13\mathrm{.}41$ An engineer designing a system to control a router for a machining process models the system so that the router's acceleration $($in in$/$s$*)$ during an interval of time is given bya $=-0\mathrm{.}40,$ where v is the velocity of the router in in$/$s$.$ When t $=0,$ the position is s $=0$ athe velocity is v $=2$ in$/$s$.$ What is the position at t $=3$ s$?$