Calculating vacation time requested

I need to calculate the vacation time requested but the date range is always May 1st through April 30th of each year.
Each new year on May 1st, the calculation would reset.

My fields are
"total time available" that is the time allowed each year
"Total time requested" its either 4, 5, 8 or 10
"total time approved" its the sum I need to calculate.  (see above)
for salary: the calculation is easy; its always the current year; for hourly, their time is May 1 - April 30.  So every May 1st, the calculation would start back at 0
"total time remaining" is formula for Time available - time approved.

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Rhonda Parriet
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