Answer and Explanation:
The preparation of the cash flow budget is presented below:
                                    Cash Flow Budget	
Particulars    Jan 2021      Feb 2021	Mar 2021      Apr 2021	May 2021      Jun 2021	
Opening Balance	$1,000	$1,400	$2,000	$4,600	$8,300	$11,700
Sales        $4,000          $4000	$6,000      $7,500  $7,500  $7,500
    (2,000 ×  2)         (2,000 ×  2)       (2,000 ×  3)    (2,500 ×  3)  (2,500 ×  3)  (2,500 ×  3)
Total Cash Inflow  $5,000	$5,400	$8,000	$12,100	$15,800	$19,200
Less: Cash payments 
Less: Bonus to employees	$1,000	$800     $800   $800   $1,500	$1,500	
(5,000 × 20%
)   (4,000 × 20%
)   (4,000 × 20%
)  (4,000 × 20%
)  (7,500 × 20%
)   (7,500 × 20%
)
Less: Overhead Cost	2,000	2,000	2,000	2,000	2,000 2,000  
Less: Direct material & Direct Labor	500      500    500    500   500 500  
Less: Fixed Cost	100	100	100	100	100	100  
Net cash generated  (A)	400  600  600  4100  3400  3400  
Opening Cash balance (B)  1000  1400  2000  2600  6700  10100  
Closing Balance (A+B)  1400	2000	4600	8300	11700	15100
Balance as on 30 June 2021 = 15100
We simply deduct all cash payments from the all cash receipts so that the ending balance or closing balance could come