; This program is purposefully broken.
; You need to fix it. 
; if an operation is impossible and cannot be fixed by fixing the syntax, 
; then just comment it out by putting ; in the beginning of the line

(define a 2)
(define b 3)

(a - b) ; subtract a from b

(plus a b) ; add a and b

* a b ; multiply a by b

(define a 5) ; give another value to a

(/ a (- b b)) ; find the result of this expression

(define (double x) (+ x x )) ; define a function to double its argument

(double a a) ; double a