Question 271973
John is 13 years less than 3 times as old as his son. Six years ago, he was 14 years more than twice as old as his son was then. How old is John? 

Let x be the age of John's son and y be John's age. Six years ago John was y-6 year old and his son was x-6. Then we have:

1.) y = 3*x - 13  and
2.) y-6 = 2*(x-6) + 14

Substitute 3x-13 for y (from 1.) in equation 2.):

3x-13 - 6 = 2*(x-6) + 14
3x-19 = 2x-12+14

Solve the above for x and then calculate y = 3x-13.