Question

john is (1)/(3) as old as his father and two years younger than his sister Kathy. The sum of the ages of the three is 67. Find the age of each.

Answer 1

Set the age of each person relative to each other. Let john's age = x. Let dad's age = y. Let sister's age = z.
\[x = (1/3)y\]
\[x = z-2\]
\[x+y+z = 67\]
Substitute:
\[x + (3x) + (x+2) = 67\]
\[5x +2 = 67\]
\[5x = 65\]
\[x = 13\]
From this we know John is 13, his sister is 15 and his father is 39.
Proof:
\[13 + 15 + 39 = 67\]

Answer 2

okaaay. thanks a lot roshan. :)