Harry started a new business on 1 January 2012. The following transactions cover his first three months in business:
1. Harry contributed an amount in cash to start the business.
2. He transferred some of the cash to a business bank account.
3. He paid an amount in advance by cheque for rental of business premises.
4. Bought goods on credit from Paul.
5. Purchased a van paying by cheque.
6. Sold some goods for cash to James.
7. Bought goods on credit from Nancy.
8. Paid motoring expenses in cash.
9. Returned some goods to Nancy.
10. Sold goods on credit to Mavis.
11. Harry withdrew some cash for personal use.
12. Bought goods from David paying in cash.
13. Mavis returns some goods.
14. Sent a cheque to Nancy.
15. Cash received from Mavis.
16. Harry receives a cash discount from Nancy.
17. Harry allows Mavis a cash discount.
18. Cheque withdrawn at the bank in order to open a petty cash account.

Required:
State which account in Harry's books of account should be debited and which account should be credited for each transaction.