Answer:
Determine the balance of the Cash account.
$3,800	Cash
Explanation:
As the total assets it's $40,000 by difference it's possible to find the total balance of cash account. 
There are 3 accounts which belongs to the asset part, Accounts Receivable, Supplies and Equipment, by difference with the total balance of Assets it's possible to find the balance of Cash.
$40,000  TOTAL ASSETS  
Minus
-$8,000  	Accounts Receivable
-$2,000  	Supplies
-$26,200	Equipment
$3,800    Cash
December 31, Year 3  
$3,800	Cash
$8,000	Accounts Receivable
$2,000	Supplies
$13,800  TOTAL CURRENT ASSETS  
$26,200	Equipment
$26,200  TOTAL NONCURRENT ASSETS  
$40,000  TOTAL ASSETS  
$8,000  Accounts Payable  
$0,000  Income Tax Payable  
$8,000  TOTAL CURRENT LIABILITIES  
$8,000  TOTAL LIABILITIES  
$17,000  Retained Earnings  
$15,000  Common Stock  
$32,000  TOTAL EQUITY  
$40,000  TOTAL EQUITY + LIABILITIES