This is a classic riddle, but as written there’s a small contradiction.
The intended riddle solution
The woman was born in 1975 BC.
Because BC years count backward, being 22 years old means she died in 1953 BC (since 1975 − 22 = 1953).
So the trick is that the calendar runs backward in BC, not forward like AD.
Why your version is confusing
If someone is both born and deceased in 1975, then they cannot be 22 years old—no matter BC or AD. That detail is usually misstated or mistyped in retellings of the riddle.
Corrected version
A woman was born in 1975 BC and died in 1953 BC. How was she 22 years old?
Answer: Because the years count backward in BC.
If you want, I can help you rewrite the riddle cleanly so it works perfectly 🙂