Spaced In Time

Once upon a time there were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

Answer: 19 years old.

Explanation:
There are 7 brothers, so there are 6 gaps of two years from youngest to oldest.
$7 + 6 \times 2 = 19$ .