Question

A father is 3 times as old as his son. After 15 years, he will be twice as old as his son. What are their
present ages?​

Answer 1

Answer:

Let the present age of son be x.

Present age of father = 3x

After 15 years,

Age of son = x+15

Age of father = 3x+15

According to Question,

2(x+15) = 3x+15

=> 2x+30 = 3x+15

=> 30-15 = 3x-2x

=> x = 15

Hence, present age of son = 15 years

Present age of father = (3×15) years = 45 years

Answer 2

Step-by-step explanation:

Let the age of the son be = x

Then the father's age is = 3x

After 15 years,

The father's age = 3x+15

The son's age = x+15

Given that after 15 years the father's age will be twice as old as son,

∴ By the problem,

⇒ 3x+15= 2(x+15)

⇒ 3x+15 = 2x+30

⇒ 3x-2x = 30-15

⇒ x = 15

Hence, the present age of the son is x=15 and his father's is 3x=3*15=45 (Ans)