From statement 3, W must be greater than 4 (for Z to be a digit). Possible values of W= 5,6,7,8,9. ——-(M)
From the above & statement 2, Y could be 4,5,6,7,8 (for W to be a digit) ————(N)
Now, from statement 1, X= W + Y + Z
Now from statement M & N, possible sum of W and Y are (9,10,11….17). Given the conditions of the questions, W+Y must be 9 where W=5 and Y=4.
Z must be 0 to make sure X is a digit.
Four digit integer=5940.