jekadva

Ответ:

Пошаговое объяснение:

4/40 + y + 16/40 = 31/40 + 6/40

20/40 + y = 37/40

y = 37/40 - 20/40

y = 17/40

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4/40 + 17/40 + 16/40 = 31/40 + 6/40

21/40 + 16/40 = 37/40

37/40 = 37/40