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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.
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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