Formula field for the Difference between 2 time values

Use the LEFT, RIGHT and FIND functions to grab the hours and minutes. Use the VALUE function to convert the strings to numbers. Multiply hours by 60 and add to minutes.

So 9.30 becomes 540 + 30 = 570

If PM convert to 24 hour equivalent (I.e add 12 to hours) 6.15 = 18 x 60 + 15 = 1095

Then subtract to get the difference and divide by 60

1095-570= 525 / 60 = 8.75