In the observation chart of the problem solution of "innovation class refining" in grade one of junior high school, the numbers corresponding to the four points of ABCD on the number axis are all integers, and their corresponding numbers are ABCD, and C-2A = 7 —.—.—.—.—.—.—.—.—.—.—> A B C D Then the origin should be a or B or C or

Think about it this way
c=2a+7
If a > 0, then C must be C > 0
Then all four numbers will be greater than 0, impossible
So a

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