The sum of the ages of 5 children is 50 years. Each children born at the intervals of 3 years. What is the difference between the eldest and the youngest child's age?

Question: The sum of the ages of 5 children is 50 years. Each children born at the intervals of 3 years. What is the difference between the eldest and the youngest child's age?
Solution:
Let the ages of children be x, (x + 3), (x + 6), (x + 9) and (x + 12) years.

According to the question,
Then, x + (x + 3) + (x + 6) + (x + 9) + (x + 12) = 50
⇒ 5x + 30 = 50
⇒ 5x = 20
⇒ x = 4

∴ Age of the youngest child = 4 years
and age of the eldest child = 4 + 12 = 16 years

The difference between the eldest and the youngest child's age = 16 - 4 = 12 years