Question

A man is 4 times as old as his son. After 20 years he will be thrice as old as his son. Find his present age.

Answer 1

Gɪᴠᴇɴ :-

A man is 4 times as old as his son. After 20 years he will be thrice as old as his son.

ᴛᴏ ғɪɴᴅ :-

• Present age of man and son

sᴏʟᴜᴛɪᴏɴ :-

Let son's present age be x & man's present age be y

then,

✞ According to 1st condition :-

• Man's present age = 4 × Son's present age

• y = 4x. ---(1)

✞ According to 2nd condition :-

➠ 20 years later :-

• Son's age = (x + 20) years

• Man's age = (y + 20) years

• Man's age = 3 × Son's age

➭ (y + 20) = 3(x + 20)

➭ y + 20 = 3x + 60

➭ y - 3x = 60 - 20

➭ y - 3x = 40. --(2)

Put the value of (1) in (2) , we get,

➭ y - 3x = 40

➭ 4x - 3x = 40

➭ x = 40 years

Put x = 40 in (1) , we get,

➭ y = 4x

➭ y = 4×40

➭ y = 160 years

Hence,

Age of :-

• Son = x = 40 years
• Man = y = 160 years

Answer 2

Answer :

Son's present age = x = 40yrs

Father's present age = 4x = 4*40 = 160yrs

To find :

Find their present ages

Explanation :

★ Let the son's age be x and his father's age be 4x

• After 20 years
• Father's age = 4x + 20
• Son's age = x + 20

**According to the given condition**

→ 4x + 20 = 3(x + 20)

→ 4x + 20 = 3x + 60

→ 4x - 3x = 60 - 20

→ x = 40 yrs