The ages of two persons differ by 30 years. If 5 years ago, the elder one was 3 times as old as the younger one, then the present age of the younger person is:

The age difference between two persons is 30 years.

5 years ago, the elder person was 3 times as old as the younger person.

Let Present age of the younger person be x years.

So, Present age of the elder person be x + 30 years.

Set up the equation based on the condition 5 years ago:

5 years ago, the younger person’s age = x - 5

5 years ago, the elder person’s age = (x + 30) - 5 = x + 25

According to the question:

x + 25 = 3 × (x − 5)

x + 25 = 3x – 15

25 + 15 = 3x – x

40 = 2x

x = 20

Thus,The present age of the younger person is 20 years.