total time

I have this setup

(H) "Dispatch Start Date" (MM/DD/YYYY)
(I) "Dispatch Start Time" (HH:MM)
(J) "Closed Date" (MM/DD/YYYY)
(K) "Closed Time" (HH:MM)
(L) "Elapsed Time" (HH:MM)

I need to find the total time spent on a job, some jobs are worked from one day to another,

example:

(H) "Dispatch Start Date" 01/01/2008
(I) "Dispatch Start Time" 20:15
(J) "Closed Date" 01/02/2008
(K) "Closed Time" 06:00
(L) "Elapsed Time" 9:45

Thanks in advance

=j1+k1-h1-i1

Got it thanks