The income statement approach to estimating uncollecteble accounts expense is used by Burgess wholesales. On march 31 the firm had accounts receivable in the amount of $630,000. The allownce for doubtful accounts had a credit balance of $3,950. The controller estimated that uncollectable accounts expense would amount to one-half of 1% of the $5,200,000 of the net sales made during march. This astimate was entered in the accounts by an adjusting entry on march 31.
On April 12, an account receivable from Conrad Stern of $3,110 was detrmined to be worthless and was written off. However on April 24, stern won several thousands dollars on a TV game show and immediately paid the $3,110 past-due account.
ANYBODY CAN SOLVE THIS PROBLEM.

There is NO PROBLEM HERE!

Something extraordinary has happened here.
A bad situation has improved and become a good situation.
We rectify this in accounting by what is known
As a REVERSAL entry.
What has been written off, can easily be brought back to life.

I suspect the problem wants the entries for the adjusting entry as well, though OP didn't actually say what the instructions were.

And 61910, we don't "solve" your problems for you. Do you have at least some idea of what to do with this?