Hello!
To figure this out I believe you'll need to use a calendar.
First, let's start w/ a leap year. as you know, when there's a leap year one extra day is added to February, making February have 29 days. Now if you were born on the 27th of February and now it's May 15, you'll be 79 days old
Now if you were born on the 27th in a normal year, you would be 78 years old.
I hope this helps!