Answer:
Zeta would have reported 20X1 sales of $4,280,000.
Explanation:
Note: the additional information in the question is correctly represented before answering the question as follows: 
                                                                  12/31/X0              12/31/X1 
Accounts receivable                              $1,000,000         $1,300,000 
Allowance for uncollectible accounts      (60,000)             (110,000) 
The explanation of the answer is now given as follows:
Since sales is equal to cash collections under the cash basis of accounting,  cash collected on accounts receivable can therefore be calculated as follows:
Ending balance = Beginning balance + Sales − Collections − Write-offs ......... (1)
Where;
Ending balance = $1,300,000
Beginning balance = $1,000,000 
Sales = $4,600,000
Collections = ?
Write-offs = $20,000 
Substituting the values into equation (1) and solve for collections, we have:
$1,300,000 = $1,000,000 + $4,600,000 − Collections − $20,000 
Collections = $1,000,000 + $4,600,000 − $20,000 - $1,300,000
Collections = $4,280,000
Therefore, Zeta would have reported 20X1 sales of $4,280,000.