Victor Pimentel uses $1,500$ per year of a certain subassembly that has an annual holding cost of $$45$ per unit. Each order placed costs Victor $$150.$ He operates $300$ days per year and has found that an order must be placed with his supplier $6$ working days before he can expect to receive that order. $6$ a$)$ The economic order quantity is units $($enter your response as a whole number$).$