[racket] simple problem with let .. I'm just NOT getting it

please help, this is driving me crazy. I sometimes run brackets together to get a clearer picture of completions 

#lang racket
(let((x 5)
     (y 2))
  (let ((x 2)
        [y x])
    (list y x)))
(let((a 2)
     (b 3))
  (let((a 2)
       (b 3))
    (printf "in this:~a~n"a)
    (printf "~nreplace this:~a~nwith-this:~a~n"a b)))

(let((in-this(file->string(car(directory-list"/home/sam/beechy"))))
     (replacements(file->list "/home/sam/REPLACEMENTS")))
  (let((replace-this(caar replacements))
       (with-this(cadadr replacements)))
    (printf "in this:~a~n"(substring in-this 0 30))
    (printf "~nreplace this:~a~nwith-this:~a~n"replace-this with-this)))


_______
OUTPUT

'(5 2)
in this:2

replace this:2
with-this:3
. read: expected a `)' to close `('
>