Explanation

We are given:

• Average age of 3 people = 25

• So, total age = 25 × 3 = 75

Their ages are in the ratio 3:5:7, which means:

Let their ages be 3x, 5x, and 7x

• Total = 3x + 5x + 7x = 15x

Set 15x = 75
⇒ x = 5

So, the ages are:

• 3x = 15

• 5x = 25

• 7x = 35

The lowest age is 15