Cox Company uses the gross method and a perpetual inventory system. Assuming the following entries, compute the amount that Cox Company received on June $21.$

June $10$ Sold goods costing $$5,400$ to Robinson Company on account, $$9,000,$ terms $\frac{5}{10},\frac{n}{30}.$ The goods are shipped FOB Shipping Point, Freight Prepaid by Seller, $$180.$

June $16$ Robinson Company returned undamaged merchandise previously purchased on account, $$500.$

June $21$ Received the amount due from Robinson Company.

Amount due from Robinson Company on June $21$: $$