Answer: Jack is 28 years old and John is 21 years old.
Explanation: Together they are 49 years old. The tricky part is the “when Jack was as old as John is now” line.
-
Jack is 7 years older than John (28 – 21 = 7).
-
7 years ago, Jack was 21 — the same age John is now.
-
At that time, John was 14.
-
Now, Jack is 28, which is exactly twice 14, so the condition is true.
