23 tháng 2 2017 lúc 11:23
\(B⋮99\Rightarrow B⋮9;11\)
\(\Rightarrow6+2+x+y+4+2+7=21+x+y⋮99\)
\(\Rightarrow x+y\in\left\{6;15\right\}\)
\(B⋮11\Rightarrow\left(6+x+4+7\right)-\left(2+y+2\right)⋮11\)
\(\Rightarrow\left(17+x\right)-\left(4-y\right)⋮11\)
\(\Rightarrow13+x-y⋮11\)
\(\Rightarrow13+\left(x-y\right)⋮11\)
\(\Rightarrow x-y=\left\{9;-2\right\}\)
\(\Rightarrow x-y=9\Rightarrow x=9;y=0\) (loại)
\(\Rightarrow x-y=-2;x+y=\left\{6;15\right\}\) (loại \(15\))
\(\Rightarrow x+y=6\Rightarrow x=2;y=4\)
Vậy \(x=2;y=4\)
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