@Shuzuchi
10 years older. She's 10 years older than her.
Edit: ok, rereading that part, I don't know whether that's a mistranslation or not. The dialog doesn't make much sense, so I probably subconsciously filled in the blanks.
@Shuzuchi hi sorry for that confusion, The process of aging is slower in elves. The speed is half of that in humans. Going by that, Lucy should be 20 in human standard. As for Dragon they age slower
@mlonethakuri which probably means Lucy is even older than that girls guess. most people when they talk about half elves assume they are elf and human. half elves lifespans typicaly are inbetween both parents a elf/human lives longer than your average human (80 years) but shorter than an average elf (several centuries)
Lucy is half dragon so her lifespan is way longer than elf but shorter than a dragon (thousands of years)
All we know is that she is less than 100 years old because her mom was busy being a hero in the holy castle war and 50 years before that her dad was disguise as a human Knight and had a whole different family. (She's not this girls distant relative Lucy is her great aunt several times over)