- The profit from the sale of x units of radiators for automobiles and y units of radiators for generators is given by P(x,y) = x²-y²+10x+4y. Find values of x and y that lead to a maximum profit if the firm must produce a total of 7 units of radiators. Selling unit(s) of radiators for automobiles and unit(s) of radiators for generators will produce a maximum profit.