Question 62307
Let the age of Ford be x yrs.

So Ford's age 3 years ago = x - 3

The Toyota's age = 2(x-3)

Age of toyota 2 yrs ago = 2(x-3)+1

Age of Ford 2 yrs ago = x-2

Thus age of BUick 2 yrs ago = 2(x-3)+ 1-(x-2)
                            = 2x - 6 + 1 - x + 2
                            = x - 3
Present age of Ford = x
Present age of Toyota = 2x - 3           [because 2(x-3)+1 +2]
Present age of Buick = x - 1              [because x - 3 + 2]

sum of the ages of these cars = x + 2x - 3 + x - 1
                              = 4x - 4
Average of these cars = (4x - 4)/3

==> (4x-4)/3 = 8
==> 4x - 4 = 24  [multiplying by 3 on either side]
==> 4x - 4 + 4 = 24 + 4
==> 4x = 28
==> 4x/4 = 28/4
==> x = 7

That is the age of Ford = 7 yrs

Age of Toyota = 2x - 3 
              = 2*7 - 3
              = 14 - 3
              = 11 yrs

Age of Buick = x - 1
             = 7 - 1
             = 6 yrs


Good Luck!!!