Trekking Company markets a climbing kit and use a perpetual inventory systems to act for its merchandise. The beginning balance of the inventory and transactions during January were as follows: January 1: Balance 18 units at $13 January 12 Purchased 30 units at $14 January 19 Sold 24 units at $17 January 20 Purchased 24 units at $17 January 27 Sold 27 units If the ending inventory is valond at $357, what anventory cost flow assumption was vised?