The cost function for selling cars is given by $C(x)=700+2x,$ the revenue function is given by $R(x)=-0\mathrm{.}001x^2+10$ and the profit function is $P(x)=R(x)-C(x)=-0\mathrm{.}001x^2+10-(700+2x).$ Use the slider along the $x-$axis to find maximum profit.