Answer: Please see explanation for answers 
Explanation:
1. Journal entry to record bad debt on January 31st
Date            Account Titles and Explanation            Debit            Credit 
Jan. 31st      Allowance for doubtful account            $1,600
 Account receivables  ( Customer C. Green)                                  $1.600
2. Journal entry to record recovery of bad debt on March 9
 A) To reinstate Amount previously written off
Date            Account Titles and Explanation                  Debit            Credit 
March 9 Account receivables  ( Customer C. Green)    $1,100
 Allowance for doubtful account                                                          $1,100
B) To record payment of account
Date            Account Titles and Explanation             Debit            Credit 
March 9            Cash                                                   $1,100
    Account receivables( Customer C. Green)                                  $1,100