Question

Chris is twice as old as Don, and next year the sum of their ages will be four times as much as Don’s age last year. Find their present ages.

Answer 1

Units are ignored in calculation.

Answer:

6 and 12 year.

Step-by-step explanation:

Let the present age of Don be a and therefore age of Chris be 2a.( since age of Chris is twice of Don's age that's a ).

Next year:

  Age of Don = present age + 1

                      = a + 1

 Age of Chris = present age + 1

                       = 2a + 1

Sum of their ages is ( a + 1 ) + ( 2a + 1 ) = a + 1 + 2a + 1 = 3a + 2.

Last year : Age of Don = present age - 1

                                  = a - 1

Given,

        Sum of their ages( of next year ) is equal to 4 times of Don's age( last year )

⇒ 3a + 2 = 4( a - 1 )

⇒ 3a + 2 = 4a - 4

⇒ 2 + 4 = 4a - 3a

⇒ 6 = a

     Hence,

             Present age of Don is 6 year

            And, present age of Chris is 2( 6 ) or 12 year