When added to the balance of Cash account, what percent of the balance of Accounts Receivable must be collected in order to pay the current balance of the Accounts Payable?

Cash account current balance: $28,515.79

Accounts payable current balance: $57,759

Accounts receivable current balance: $104,065.65

The book says the answer is: 28.10%, but I have no idea how they got that answer. Please help