He offered trade discount.

When we sell the goods, immediately we can get cash at once. So no occurs had debts in the business.

(i) Invoice is a business document or bill or statement giving the details of goods sold as to the quantity, quality, price, total value, etc.
(ii) Thus the invoice is a source document of prime entry both for the buyer and seller. It is purchase invoice or inward invoice for the buyer and sales invoice or outward invoice for a seller

Journal Proper is a residuary book which contains record of transactions which do not find a place in the subsidiary books such as cash book, purchases book, sales book, purchases returns book, sales returns book, bills receivable book and bills payable book.

(i) A credit note is prepared by the seller and sent to the buyer when goods are returned indicating that the buyer's account is credited in respect of goods returned.
(ii) Credit note is a statement prepared by a trader who receives back from his customer the goods sold.
(iii) It contains details such as the description of goods returned by the buyer, quantity returned and also their value.

(i) A 'debit note' is a document, bill or statement sent to the person to whom goods are returned or from whom an allowance is claimed.
(ii) It contains the description and details of goods returned, name of the party to whom goods are returned and net value of the goods so returned with reason for return or allowance claimed.

(i) Bills Receivable Book :
     (a) Bills receivable refers to Bills drawn, the payment for which has to be received.
     (b) Such bills are drawn on debtor for a specified amount payable at sign on or after specified period.
     (c) Bills receivable book contains the details of bills drawn and its disposal.
(ii) Bills Payable Book:
      (a) Details recorded in the bills payable book are the names of the parties whose bills are accepted, date of the bills payable, due date, amount, etc.
      (b) The individual accounts of the parties whose bills are accepted will be debited with the corresponding amount in the bills payable book.

The important features of a bill of exchange are as follows :
(i) It is a written document.
(ii) It is an unconditional order.
(iii) It is an order to pay a certain sum of money.
(iv) It is signed by the drawer.
(v) It bears stamp or it is drafted on a stamp paper.
(vi) It is to be accepted by the acceptor.
(vii) The amount of the bill is paid to the drawer or the endorsee.

(a) Endorsement of a bill :
(i) Endorsement means signing on the face or back of a bill for the purpose of transferring the title of the bill to another person. The person who endorses is called the "Endorser".
(ii) The person to whom a bill is endorsed is called the "Endorsee". The Endorsee is entitled to collect the money.
(b) Discounting of a bill :
(i) When the holder of a bill is in need of money before the due date of a bill, he can convert it into cash by discounting the bill with his banker. This process is referred to as the discounting of bill.
(i) The banker deducts a small amount of the bill which is called discount and pays the balance in cash immediately to the holder of the-bill.

The advantages of maintaining subsidiary books can be summarised as under :
(i) Proper and systematic record of the business transactions : All the business transactions are classified and grouped conveniently as cash and non cash transactions, which are further classified as credit purchases, credit sales and returns etc.
(ii) Convenient posting: All the transactions of a particular nature are recorded at one place, i.e., in one of the subsidiary books. For Example: All credit purchases of goods are recorded in the purchases book and all credit sales of goods are recorded in the sales book.
(iii) Division of work: As journals are sub-divided, the work will be sub-divided and different persons can work on different books at the same time and the work can be speedily completed.
(iv) Efficiency: The sub-division of work gives the advantage of specialisation. Thus specialisation leads to efficiency in accounting work.
(v) Helpful in decision making: Subsidiary books provide complete details about every type of transactions separately. Hence the management can use the information as the basis for deciding its future actions.
(vi) Prevents errors and frauds: Internal check becomes more effective as the work can be divided in such a manner that the work of one person is automatically checked by another person. With the use of internal check, the possibility of occurrence of errors or fraud may be avoided or minimised.
(vii) Availability of requisite information at a glance : The maintenance of subsidiary books helps in obtaining the necessary information at a glance.

29^th may 2017 transaction is purchase of an asset. Hence the transaction will not be recorded in the purchases book.