3.7 To encoursge prompt payment of invoices, manufacturers and wholesalers offer casi discounts for payments in advance of the due date. The following typical terns may be printed on the sales invoice: 3/10,n/30. Goods billed on this basis sre sabject to a cash discount of 3% if paid for within 10 days. Otherwise, the full a-mount must be paid not later than 30 days from the date of invoice. Suppose that a merchant receives an invoice for $2800 with the above terms. (a) What is the highest simple interest rate at which he can borrow in order to take advantage of the cach discount? (b) What profit can the merchant realize by borrowing \#ocey at 18% and paying the invoico on the merchant realize by boirowling