Fong Sai-Yuk Company sells one product. Presented below is information for January for Fong Sai-Yuk Company.

Jan. 1 : Inventory 130units at $5 each

Jan. 4 : Sale 106units at $8 each

Jan. 11 : Purchase 151units at $7 each

Jan. 13 : Sale 116units at $9 each

Jan. 20 : Purchase 163units at $7 each

Jan. 27 : Sale 100units at $11 each

Fong Sai-Yuk uses the FIFO cost flow assumption. All purchases and sales are on account.

a.) Assume Fong Sai-Yuk uses a periodic system. Prepare all necessary journal entries, including the end-of-month closing entry to record cost of goods sold. A physical count indicates that the ending inventory for January is 122 units.

b.) Assume Fong Sai-Yuk uses a perpetual system. Prepare all necessary journal entries.

c.) Compute gross profit using the perpetual system.