Solutions to Problems


(define biggie-size
  (lambda (combo)
    (+ 4 combo)))

(define unbiggie-size
  (lambda (combo)
    (- combo 4)))

(define biggie-size?
  (lambda (combo)
    (> combo 4)))

(define combo-price
  (lambda (combo)
    (if (biggie-size? combo)
	(+ .5 (* 1.17 (unbiggie-size combo)))
	(* 1.17 combo))))

(define empty-order
  (lambda ()
    0))

(define add-to-order
  (lambda (order combo)
    (+ (* 10 order) combo)))

(define order-size
  (lambda (order)
    (if (= order 0)
	0
	(+ 1 (order-size (quotient order 10))))))

(define order-price
  (lambda (order)
    (if (= order 0)
	0
	(+ (combo-price (remainder order 10))
	   (order-price (quotient order 10))))))