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abc; bca si cab sunt cu bara deasubra.
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(abc + bca + cab) : (a + b + c) =
[(100a + 10b + c) + (100b + 10c + a) + (100c + 10a + b)] : (a + b + c) =
= (100a + 100b + 100c + 10a + 10b + 10c + a + b + c) : (a + b + c) =
=[100(a + b + c) + 10(a + b + c) + (a + b + c)] : (a + b + c) =
= (a + b + c)(100 + 10 + 1) : (a + b + c) =
= 111(a + b + c) : (a + b + c) = 111