A father is three times as old as his son. After twelve years, his age will be twice as that of his son then. Find their present ages.

Match the items on the right to the items on the left.

STEP 1

STEP 2

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STEP 5

Let the present age of father be ‘a’ and present age of son be b. Given, father is three times as old as his son. ⇒ a = 3b ---- (1)

Also, after twelve years, his age will be twice as that of his son then.
12 years later age of father will be a+12 and son will be b+12.

⇒ a + 12 = 2(b + 12)
⇒ a+12 = 2b + 24 ⇒ a = 2b + 12

Put the value of a from eq. (1)
⇒ 3b = 2b + 12
⇒ 3b - 2b = 12
⇒ b = 12

Put the value of a in eq. 1 to get, a=3b a=3(12) a=36
Thus, present age of father is 36 years and present age of son is 12 years.