Question

10.
Father's present age is three times his son's age. Six years back the
father's age was five times the son's age. Their present ages are:
12 and 36
13 and 39
B.
D.
21 and 63
12 and 40
C.​

Answer 1

Answer:

Their present ages are 12 and 36.

Answer 2

Answer :

• Son's present age = 12 years
• Father's present age = 36 years

Given :

• Father's present age is three times his son's age. Six years back the father's age was five times the son's age.

To Find :

• Their present ages.

Solution :

Let

• Son's present age = x
• Father's present age = 3x

Six years ago

• Father's age = (3x - 6)
• Son's age = (x - 6)

It is given that

• Six years ago, father's age was five times the son's age.

Equation formed

• (3x - 6) = 5 (x - 6)

According to question :

→ 3x - 6 = 5x - 30

→ - 6 + 30 = 5x - 3x

→ 24 = 2x

→ x = 24/2

→ x = 12

Now

• Present age of son = x = 12 years
• Present age of father = 3x = 12 × 3 = 36 years

Verification :

→ 3x - 6 = 5 (x - 6)

→ 3 (12) - 6 = 5 (12 - 6)

→ 36 - 6 = 5 × 6

→ 30 = 30

Hence, verified !