Help with LiveCycle

Hello, I need some assistance with a pdf form I have created in LiveCycle.  I need assistance on how to figure out calculating the total number of hours from 2 fields, e.g., Start time (HH:MM) and End time: (HH:MM) = Total time (number field) e.g., Start time is 2:10 pm, End time is 4:10 p.m. = total hours = 2   I received a request for this "if possible" can the time be in 10 minute increments.     I am the creator of forms for our department and I've had no formal training and my knowledge level is beginner, but I get through with this community help and youtube videos.  Any help is appeciated.   Thank you in advance.