6. Figure1101/414 25/4
Figure 2 5 2 5/4 1 2 3/4
7 First question: Solution: The formula is (10a+b)-(10b+a) = 9 (a-b). I know it can be divisible by 9, because it is a multiple of 9.
Divisible by 9.
The second question: the sum of the solutions is (10a+b)+(10b+a) = 1 1 (a+b), so I understand that the sum of these formulas can be11integer.
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