Snowball Company reported beginning inventory of 100 units at a unit cost of $20. It engaged in the following purchase and sale transactions during 2009:
Jan. 14 Sold 20 units at unit sales price of $45 on open account.
April 9 Purchased 15 additional units at unit cost of $20 on open account.
Sept. 2 Sold 45 units at sales price of $50 on open account.
At the end of 2009, a physical count showed that Snowball Company had 50 units of inventory still on hand.

Required:
Record each transaction, assuming that Snowball Company uses
(a) A perpetual inventory system and
(b) A periodic inventory system (including any necessary entries at the end of the accounting period on December 31).