Eighteen years ago, a father was three times as old as his son. Now the father is only twice as old as his son. Then the sum of the present ages of the son and the father is-
বিকল্পসমূহ (নিজের উত্তর যাচাই করতে ক্লিক করুন):
সঠিক উত্তর
2 (108)
বিস্তারিত ব্যাখ্যা ও বিশ্লেষণ:
Solution:
Let the father's current age be x years,
and the son's current age be y years.
First condition: Eighteen years ago, the father was three times as old as the son.
⇒ x - 18 = 3(y - 18)
⇒ x - 18 = 3y - 54
⇒ x = 3y - 36 … (1)
But also, rearranging this gives:
3y = x + 36 ⇒ y = x/3 + 12 … (1a)
Second condition: Currently, the father is twice as old as the son.
⇒ x = 2y … (2)
Substituting (1a) into (2):
x = 2(x/3 + 12)
⇒ x = 2x/3 + 24
⇒ x - 2x/3 = 24
⇒ x/3 = 24
⇒ x = 72
Now from equation (2): y = x / 2 = 72 / 2 = 36
∴ Father's age = 72 years
Son's age = 36 years
Total of their present ages = 72 + 36 = 108 years
