Answer and Explanation:
The Preparation of cash budget for each of the months of July, August, and September is shown below:-
                                               Cash budget
                              For the month of July, August and September
                                              July           August          September
Beginning cash balance   $15,000      $15,000         $25,505
Cash receipts from 
customer (Working note) $57,800      $67,200        $73,600
Total cash available         $72,800      $82,200       $99,105
Less:
Cash disbursements
Direct Materials                 $16,160         $13,440         $13,760
Sales commission             $6,400         $8,000          $4,800
(10% of sales)
Office salaries                   $4,000          $4,000          $4,000
Rent                                    $6,500         $6,500          $6,500
Direct Labor                       $4,040         $3,360           $3,440
Overhead Cost                 $20,200       $16,800         $17,200
Interest on bank loan    
For July (5,000 × 1%)             $50  
For August                                                  $46            
($5,000 - $4,550) × 1%))
For September                                                                  $0
Preliminary Cash
balance                                    $15,450    $30,055      $49,405
Repayment of loan to 
Bank                                          $450        $4,550
                                                                 ($5,000 - $450)
Ending cash balance              $15,000     $25,505     $49,405
Working Note
The ending balance of the particular month should be treated as a opening balance of next month 
August ending balance will be forwarded in Sept as a opening balance.
Working Note 
                                         July           August          September
Sales                            $64,000      $80,000            $48,000
Less:
Ending accounts
receivable 
(80% of sales)            $51,200       $64,000             $38,400
Cash sales                 $12,800        $16,000              $9,600
Last month cash 
collection                   $45,000         $51,200          $64,000
Cash receipts from 
customer                    $57,800      $67,200        $73,600
Therefore we added the cash receipts as it increase the cash balance and deduct all cash payment as it decrease the cash balance