Ответ:

Пошаговое объяснение:

12/14 = 6/7

50/75 = 2/3

112/80 = 7/5

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a) 5/6 - 3/4 = 10/12 - 9/12 = 1/12

б) 9/14 + 8/21 = 27/42 + 16/42 = 43/42 = 1 1/42

в) 3/9 + 2/7 - 1/3 = 1/3 - 1/3 + 2/7 = 2/7

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2/3 + x = 5/7

x = 5/7 - 2/3

x = 15/21 - 14/21

x = 1/21

3/8 - x = 4/7

x = 3/8 - 4/7

x = 21/56 - 32/56

x = -11/56

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