1.

Five year ago a man was seven times as old as his son. Five year hence, the father will be three times as old as his son. Fins their present age.

Answer»

Solution

Let the past age of son = 'x'

Let the past age of father = 7x

So,

   Present ages are x + 5 and 7x + 5

   Future age of son = x + 10

   Future age of father = 7x + 10

Given,

         ⇒ 7x + 10 = 3 (x + 10)

         ⇒ 7x + 10 = 3X + 30

         ⇒ 7x - 3x = 30 - 16

         ⇒ 4x = 20

         ⇒ x = 5

Let US verify our answer,

        ⇒ 7 × 5 + 10 = 3 (5 + 10)

        ⇒ 35 + 10 = 3×5 + 3×10

        ⇒ 45 = 15 + 30

        ⇒ 45 = 45

LHS = RHS

Hence it is verified.

   

    ⇒ 7x = 7 × 5 = 35

    ⇒ x+5 = 5 + 5 = 10

    ⇒ 7x + 5 = (7 × 5)+ 5 = 35 + 5 = 40


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