Each foot of carpet purchased from a 12-foot-wide roll costs $36. If a fraction of a foot is purchased, a customer does not pay for the extra amount. For example, if a customer wants 14 feet of carpet and the salesperson cuts off 14 feet 4 inches, the customer does not pay for the extra 4 inches. 

(a) How much does 9 feet 8 inches of carpet from this roll cost? 

(b) Using the greatest integer function, write a for- mula for the price P of x feet of carpet.