You required 100 tiles in total

As per question we have to find maximum difference possible between white and black tiles.

So, we have to find, as per condition, maximum white tiles(black) can be used and minimum blac tiles(white) tiles that must be used.

In any case, maxium black and white tiles that can be used to form the square is 90.( 9 tiles of same color in any row or column:: 9 * 10).

and minimum blac or white tiles that can be used to form the squaare is 10( 1 tiles every row or column = 1 * 10 )

90 - 10 = 80

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Kudos if any of my post helps you !!!