A sales representative for a company that produces blenders can sell $x$ units of their deluxe model if the price is $p=D(x)=87\mathrm{.}2-0\mathrm{.}05x$ dollars. The total cost for these blenders is given by $C(x)=0\mathrm{.}08x^2+5\mathrm{.}5x+6000$ dollars. Determine the marginal profit for $141$ blenders.