leaky pipe, a local retailer of plumbing supplies, faces demand for one of its SKUs at a constant rate of $38,500$ units per year. it costs leaky pipe $15$ to process an order to replenish stock and $$3$ per unit per year to carry the item in stock. stock is received $3$ working days after an order is placed. no backordering is allowed. assume $360$ working days a year.

what is demand during lead time