Do decrease in accounts receiveable decrease sales?

Generally, those two accounts tend to move in the same direction. It is typically driven by Sales, though.

If Sales in a year increase, it would be expected that Accounts Receivable (A/R) would increase as well because typically a proportion of Sales are paid in cash, while another proportion is charged to credit.

If a company's Sales are generally made up by 1/2 cash and 1/2 credit, if Sales increased substantially in the year, we would expect A/R to increase as well.

If, however, Sales in the year plummeted, we would also expect A/R to decrease from the previous year.

(This is also assuming the company has not changed its policies regarding how it extends credit to customers, and is collecting its receivables in a timely manner.)