Multiple choice

Five years hence, the age of jacob will be three times that of his son. Five years ago, Jacob's age was seven times that of his son. What are their present ages?

  1. Present age of Jacob: $50$ years and Present age of Jacob's son: $15$ years
  2. Present age of Jacob: $50$. years and Present age of Jacob's son: $10$ years
  3. Present age of Jacob: $40$ years and Present age of Jacob's son: $10$ years
  4. Present age of Jacob: $35$  years and Present age of Jacob's son: $15$ years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let J be Jacob's age, S be son's age. (J+5) = 3(S+5) => J = 3S + 10. (J-5) = 7(S-5) => J = 7S - 30. 3S + 10 = 7S - 30 => 4S = 40 => S = 10. J = 40.

AI explanation

Let the son's present age be x years and Jacob's present age be y years. From the first condition, y + 5 = 3 times (x + 5), which simplifies to y = 3x + 10. From the second condition, y - 5 = 7 times (x - 5), which simplifies to y = 7x - 30. Equating the two expressions gives 3x + 10 = 7x - 30, meaning 4x = 40 and x = 10. Substituting x into the first equation gives y = 40, so Jacob is 40 years old and his son is 10 years old.

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