A person was 15 years old in 1990, in 1995 he was 10 years old, how is this possible?

Because the dates are 1990BC and 1995BC.

He time travelled from 1985 to 1995 then when he was 15, he travelled back to 1990.

That's aside from the obvious BC answer.

The years are counted B.C. Therefore the person was born in 2005 B.C., was 5 years old in 2000 B.C., 10 in 1995 B.C., and 15 in 1990 B.C.

The person was living in the time called "BC", which means Before Christ. In that ancient time, as the years go by, it will lessen instead of being added upon. Like:

1995=15years old

1994=16years old

1993=17years old

Sort of like that.

a million is corn 2 i'm caught on you ( yet while i became the fly i could be announcing are you to cheesy to enable me bypass? ) 3 could rely on how lots there is left to end and how lots is outfitted. 4 is bc age.

You saw Benjamin Button waaaay too many times.

They're not the same person.

This is the stupidest thing everrrr

the person is BENJAMIN BUTTON! hahaha :P