Question

(3 8/21+k)-5 13/21=2 4/7

Answer 1

(3 8/21 + k) - 5 13/21 = 2 4/7
3 8/21 + k = 2 4/7 + 5 13/21
3 8/21 + k = 2 12/21 + 5 13/21
3 8/21 + k = 7 25/21
k = 7 25/21 - 3 8/21
k = 4 17/21
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Проверка: (3 8/21 + 4 17/21) - 5 13/21 = 2 4/7
                   7 25/21 - 5 13/21 = 2 12/21 = 2 4/7