(define (make-vect x y)
  (cons x y))

(define (xcor-vect v)
  (car v))

(define (ycor-vect v)
  (cdr v))

(define (add-vect v1 v2)
  (make-vect (+ (xcor-vect v1)
                (xcor-vect v2))
             (+ (ycor-vect v1)
                (ycor-vect v2))))

(define (scale-vect s v)
  (make-vect (* s (xcor-vect v))
             (* s (ycor-vect v))))

(define (sub-vect v1 v2)
  (add-vect v1
            (scale-vect -1 v2)))

