Answers

2014-10-24T10:39:21+08:00
Let
                present      six years ago          
alex' age       x                 x-6                         
father         5+ 2x            (5+2x) - 6  becomes  2x-1                        

1/3(2x-1) = x-6      since six years ago, alex's age is 1/3 of his father's age
2x-1 =  3x -18      solve for x

x= 17 (alex's age)
5 + 2x = 39 (father's age)
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