Define a function FindEmployeeTax$()$ that takes one integer parameter as a person's age, and returns the person's tax percent as a double. The tax percent is returned as follows:

If the person's age is at least $80$ years old, then the tax percent is $0\mathrm{.}05.$

If the person's age is more than $60$ and less than $80$ years old, then the tax percent is $0\mathrm{.}21.$

Otherwise, the tax percent is $0\mathrm{.}45.$