Time In & Time Out (For Payroll System)

I have this Time In and Time Out Text1.text = Time in Text2.text = Time out Text3.text = Total number of hours work My problem is how can I calculate the total time of work of an employee? Example: I put a 8:38 am in Time In then 5:00 pm in Time Out. I want to gather a code which can actually calculate the total number of hours work of an employee. Because if I add this two numbers it will appear 13:38 instead of 7:22 total number of hours. If any one know or have an idea please kindly post it. Thank you in advance ^_^