Scheme/Drracket, avoid using let, still not evaluating same function twice

Question

I have a coding class assignment i am not able to solve :(

(define f
  (lambda (x)
    (i (g x) (h (g x)))))

i, g and h are just arbitrary function names. This is the code and i am required to rewrite it such that (g x) is evaluated only once but without using let (or any variant of it) using only define and lambda as predefined functions. I am also not allowed to take calculations out of f, that is, alls calculations must happen inside that function.

Answer 1

The easy way is

(define f
  (lambda (x)
    (define intermediary (g x))
    (i intermediary (h intermediary))))

and the more complicated would be

(define f
  (lambda (x)
    ((lambda (intermediary) ; anonymous procedure
       (i intermediary (h intermediary)))
     (g x))))

or, avoiding the anonymous procedure and giving it the name sub:

(define f
  (lambda (x)
    (define sub
      (lambda (intermediary)
       (i intermediary (h intermediary))))
    (sub (g x))))