Complete the following function definition:

  ;; add-tax : Number -> Number 
  ;; add the sales tax to a given amount; 
  ;; assume the sales tax rate is 5%
  (define (add-tax net-amount)




    )


  ;; Examples/tests: 
  (equal? (add-tax 100) 105)
  (equal? (add-tax 200) 210)

Solution:

;; [PT 1] for one of these (or equivalent): 
  (* 1.05 net-amount) 
or 
  (+ net-amount (* .05 net-amount)) 

What will DrScheme's Interactions Window show when you run this complete program:

  (define NAME "Matthias")

  ;; closing : String -> String 
  ;; create a closing for a letter,
  ;; given the closing phrase 
  (define (closing txt) (string-append txt " \n" NAME))

  (string=? (closing "Sincerely")
            "Sincerely \nMatthias")
  ;; one could also test, but I won't:
  ;; (string=? (closing "Regards,")
  ;;           "Regards, \nMatthias")

Solution: true ;; [PT 1]