Formula Needed to calculate Vacation Time Based on start date

Hi there,

I am not so good with excel and need to create a few formulas:

1- that will calculate an employee's vacation entitlement for the year, based on their start date. They are entitled to 10 days per year.

2- In addition, I also need another formula to calculate how much vacation was earned in a year if an employee leaves based on that date.
It may occur that someone starts and ends employment in one year so that's another caveat to consider.

Any help on this??