;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname 13.7.1) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
; Exercise 13.7.1
; 18-to-25? : number (age) -> Boolean
(check-expect (18-to-25? 15) false)
(check-expect (18-to-25? 18) true)
(check-expect (18-to-25? 20) true)
(check-expect (18-to-25? 25) true)
(check-expect (18-to-25? 27) false)

(define (18-to-25? age)
  ; age a number
  ; 18 a fixed number we’ll need
  ; 25 another fixed number we’ll need
  ; (>= age 18) a Boolean
  ; (<= age 25) a Boolean
  (and (>= age 18)
       (<= age 25))
  )