The Wilsons have triplets and another child who is thirteen years old. The sum of the ages of their children is 31. How old are the triplets?

The age of each triplet if 6 years.

Step-by-step explanation:

Let us assume the age of first child in triplet = m years

Since, the children are triplet, so age of 3 children are SAME.

⇒The age of second child in triplet = m years

and, The age of third child in triplet = m years

Also, the age of fourth children = 13 years

So, sum of age of all four children =

Sum of age of all triplets + Age of fourth child = m + m + m + 13 = 3 m + 13

Given: The sum of the ages of their children is 31.

⇒ 3 m + 13 = 31

or, 3 m = 31 - 1 3 = 18

or, m = 18/3 = 6

or, m = 6 years

Hence the age of each triplet if 6 years.