Joined: 14 Jun 2006 Posts: 331 Location: Jacksonville, FL
This is an addition problem. y must be either a 1 or a 2 in the answer (yxxxz) when you add the three numbers(x+y+z). In order for z to be in the answer (yxxxz), x + y must add up to ten. If x + y must add up to 10, then y has to be 1 (because 10 + z would not be greater than 19). If y is 1, then x must be a 9. z has to be one less the x because you carry the one to the second colume to make 9.