Simpson expects to sell more than $20,000$ sandwiches in $20$X$3.$In December $20$X$3$ Simpson has the opportunity to bid on a special order for sandwiches for a party.

Simpson wants to do the party for marketing purposes and is willing to sell the sandwiches for this party for less than the normal $$15\mathrm{.}00$ per sandwich.$$

Accepting the special order will not reduce any sales to normal customers.$$

What is the lowest selling price $($per sandwich$)$ Simpson should be willing to consider for this special order?$$