Open Question: How would I journalize these transactions, and which journal would you put them into?

A.) Issued Credit Memo No. 107 to My Fitness, for merchandise returned on invoice No. 304 of April 8, $500.00. Cost of Merchandise Sold is $300.00. B.) Received Credit Memo No. 432 from Fitness Equipment for merchandise returned, $360.00 Also, Question C.) When you have the general ledger, what is the difference between the Merchandise Inventory and the Cost or Merchandise Sold Ledger, and how would you post to each Ledger?? Thank you for your help! :)