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CEMC Gauss (Grade 8), 2011

Number theory Difficulty 2.0 Junior Find the answer Canada

In the diagram, each of the integers 1 through 9 is to be placed in one circle so that the integers in every straight row of three joined circles add to 18. The 6 and 1 have been filled in. The value of the number represented by $x$ is

(A) $4$ (B) $5$ (C) $7$ (D) $8$ (E) $3$

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