A toy manufacturer produces an inexpensive doll (flopsy) and an expensive doll (mopsy) in units of \(x\) hundreds and \(y\) hundreds respectively. Suppose it is possible to produce the doll in such a way that \(y = \frac{82-10x}{10-x}, 0 \le x \le 8\) and that the company receives twice as much for selling a mopsy doll as for selling a flopsy doll. The level of production for both flopsy and mopsy dolls for which the total revenue derived from selling these dolls is maximized is given by :