Hello Hilary,
Thank you for your prompt response.
I have tried the function given on
http://www.braintrove.com/id/95
and below is the formula i created as given.
translate(addSeconds(@Coaching_Out_Time, -1 * (substring(@Coaching_In_Time, 1, 2) * 3600 + substring(@Coaching_In_Time, 4, 2) * 60 + substring(@Coaching_In_Time, 7, ...