Answer:
the amount of the adjustment in the Allowance for
Bad Debts​ account  $3.000
Explanation:
Initial Balance Â
Allowance for Uncollectible Accounts  $ 9.000
END Balance Â
Allowance for Uncollectible Accounts  $ 12.000
The adjustment entry in the accountig will be
Bad debt expense  $ 3.000 Â
Allowance for Uncollectible Accounts  $ 3.000