Решите уравниние, плизз

Question

Решите уравниние, плизз

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Answer 1

(4 8/21+z)-7 13/21=2 12/21
4 8/21+z=2 12/21+7 13/21
4 8/21+z=9 25/21
z=9 25/21-4 8/21
z=5 17/21