[racket] exercise 57 of the Desiging programms second Edition

Hello,

Is this a good answer to exercise 57 of the Second Edition book.

1) (define-struct time-midnight (hour minutes seconds))

2)  Struct ->  Struct.
      A programm which calculates the time with 12 'o clock at the 
evening as starting point.
      Given ( 1:12.23)  expected ( 1:12:23)
      Given ( 14:00:34) expected ( 14:00:34)
     (define (time-from-midnight ( time-midnight) x)

Regards,

Roelof