Trial Balance and Rectification of Errors

Rectify the following errors :
(a) Depreciation provided on machinery ` 4,000 was not posted.
(b) Bad debts written off ` 5,000 were not posted.
(c) Discount allowed to a debtor ` 100 on receiving cash from him was not
posted.
(d) Discount allowed to a debtor ` 100 on receiving cash from him was not
posted to discount account.
(e) Bill receivable for ` 2,000 received from a debtor was not posted.