Question 535919
Tom is twice as old as Dick. 
Dick is four years younger than Harry.
Harry is eight years younger than Tom. 

let tom be x years
Harry x-8
Dick (x-8)-4

Tom = 2 * Dick
x= 2((x-8)-4)
x=2x-16-8
-x=-24
x=24 Tom's age
Harry = 24-8=16 years