David Weaver
Column 1 :9-2 (sums of the digits in the first colum) = 7
Column 2: 13-6=7
Column 3: 17-10 = 7

I may have not said that right = the difference of the sums in the columns, or some such thing, above is what i was attempting to get across. Somehow, despite all of the math in college, I didn't learn to communicate clearly even regarding arithmetic.