How do I find these??

In its first month of operations, Literacy for the Illiterate opened a new bookstore and bought merchandise in the following order: (1)220 units at $6 on January 1. (2) 640 units at $7 on January 8, and (3)940 units at $8 on January 29. Assume 1.185 units are on hand at the end of the month, calculate the cost of goods available for sale ending inventory, and cost of goods sold under the (a) FIFO, (b) LIFO, and (c) weighted average cost flow assumptions. Assume a periodic inventory system is used