Set working day at 10hours period with zohocurrentdate?

Set working day at 10hours period with zohocurrentdate?

The zoho variable Zoho.Current.Time and Zoho.Current.Date is very good and I use it to input time and date as a hidden field and also how long it took to close the ticket (with last modified time):

"Length" field:
((Modified_Time - Date_Time) / (1000 * 60 * 60)).round(2)

What I get is a number of hours, but what if I want to limit those hours
to 7am 7pm?

eg when I get "Length" = 240 hours, it is since the ticket is opened, but
not in real business hours from 7am to 7pm...

If I open a ticket today at 7am and close it tomorrow at 7am, I'll get
length=24

When the real length was 12...