A seller is considering extending trade credit to an existing customer that buys on cash terms. The customer has just placed a sales order $($cash terms$)$ for immediate delivery of $400$ units at a sales price per unit of $$100.$ The customer states that they will increase their sales order by $10$ units if they receive a $90-$day credit period. Variable costs are $$65$ per unit and involve an immediate cash outflow. If the seller has an annual opportunity cost rate of $7\mathrm{.}3\%,$ what is the NPV of extending credit to the customer? $($Ch$5$: $4$ points$)$