2x + 2y + 10z = 10
x + y + 5z -3u = -1
6z + 3y + 2u = 1
y + 2w + 2z = 13
When you solve this system using Gauss-Jordan Elimination, what is the sum of the elements
in the column that corresponds to the variable z? (That is, the third column if you use the
order x, y, z, u, w).