Riddle Snapshot
A handwritten note poses a timeline mystery:

• In 1990, a person is 15 years old.
• In 1995, that same person is 10 years old.
  At first glance, it seems impossible—people usually get older as years increase.

Why It Seems Impossible
In the modern way we talk about dates (AD/CE), time moves forward:

• 1990 → 1995 is 5 years later
  So the person should be older, not younger.

The Key Twist
The riddle is using BC (B.C.), where the years count backward as time moves forward.

In a BC timeline:

• 1995 BC happens earlier than 1990 BC
• Moving from 1995 BC to 1990 BC is moving forward in time (toward year 0)

The Correct Answer
Both years are BC.

Here’s how the ages line up:

• In 1995 BC, the person is 10.
• Five years later (moving forward in time), in 1990 BC, the person is 15.

Quick Timeline Check

• 1995 BC (age 10) → 1994 BC (age 11) → 1993 BC (age 12) → 1992 BC (age 13) → 1991 BC (age 14) → 1990 BC (age 15)

Conclusion
This puzzle works because the calendar is reversed in BC dating:

• The year number gets smaller while time moves forward
  So it’s completely consistent for someone to be 10 in 1995 BC and 15 in 1990 BC.