Special order

Zenon Inc. has determined the following cost data:

The normal selling price is $$25$ per unit. The company has an opportunity

to bid on a one$-$time only sale of $1,000$ units. The variable selling costs would

be replaced by a bulk shipping charge of $$500.$ If excess capacity exists,

and this order would not disturb regular sales, what would be the company's

incremental cost per unit of accepting this special offer?