Prepare journal entries to record these transactions:

Mar. $21$ Accepted a $$7,150,$ six$-$month, $4\%$ note dated today from Bradley Brooks in granting a time extension on his past$-$due account.

Sept. $21$ Brooks dishonoured his note when presented for payment.

Dec. $31$ After exhausting all legal means of collection, wrote off Brooks$$s account against the Allowance for Doubtful Accounts.