On April 30, Holden Company had an Accounts Receivable balance of $18,000. During the month of May, total credits to Accounts Receivable were $52,000 from customer payments. The May 31 Accounts Receivable balance was $13,000. What was the amount of credit sales during May?

Prepare a T account and post known entries on relevant sides and you will get the answer as 45,000

Another way to look at this is to start with your beginning balance plus amounts of credit sales minus customers payments equals your ending accounts receivable balance. Since you are trying to find the amount of credit sales you have to rewrite your formula.

So your ending accounts receivable balance minus your beginning account receivable balance plus your customer payments equals your amount of credit sales.