dealing with finanical accouting

Assume Anderson's General Store bought, on credit, a truckload of merchandise from American Wholesaling costing $24,000. If Anderson's paid National Trucking $750 cash for transportation, immediately returned goods to American Wholesaling costing $1,300, and then paid American Wholesaling within the 3/30,n/60 purchase discount period. How much did this inventory cost Anderson's? Assume Anderson's uses a perpetual inventory system