I have no idea what this test is asking...maybe my English is poor. How do you think about it? Also, it would be appreciate if you can also show me the solution.
The correct answer is as indicated in the image.
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There are $r(r+1)$ boxes. You remove the $r+1$ boxes from the 4th row and the $r$ boxes from the 7th column. However, in doing so, you counted the one box in the 4th row and 7th column twice, so we must add $1$ back. Hence there are $r(r+1)-r-(r+1)+1=r^2-r$ total boxes left. The part about $r>10$ is seemingly there just to make the 4th row and 7th column make sense, but other than that is just to trick you I suppose.
doppz
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...and the numbering of the rows and columns is even more irrelevant than the $r>10$ condition. – Silverfish Nov 05 '13 at 02:32
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I believe OP's question was more about the logical meaning of "neither $x$ nor $y$"(Just maybe) – chubakueno Nov 05 '13 at 02:32
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Yes @chubakueno, I did not understand the in the context "Neither x nor y" means to remove them. – David S. Nov 05 '13 at 02:44