formula needed to add a number of years to a date

I need a formula the will allow me to add years, in number form with decimals, to a birthdate and give me the date the person will turn that age. For example, cell A1 has a dte of birth in it, say July 1/1975 , cell B1 has 25.5 in it, I need the formula for C1 that will tell me, in date form, the day the person turned or turns 25.5

Thanks