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Question
Three years ago, a man was 5 times the age of his son. Four years hence, he will be thrice his son's age. Find the present ages of the man and his son.
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Solution
Let the present age of the man be M years and his sons age be S years.
Then, as per the question description,
M - 3 = 5 (S-3 ) ...... (i)
M + 4 =3 (S+4 ) ...... (ii)
From (i), we get: M + 12 = 5 S
⇒ S = `("M" + 12)/5` .........(iii)
From (ii), we get: M - 8 = 3S
Putting (iii) above, we get: M - 8 = `(3 (M + 12))/5`
⇒ 5M - 40 = 3M + 36
⇒ 2M = 76
⇒ M =38 years and hence, S= 10 years
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