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.

Question

anonymous · Answer

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:
$$13 + 15 + 39 = 67$$

anonymous · Answer

okaaay. thanks a lot roshan. :)