найдите х:х : 2 1/4 - 7*х = 1 3/8

х : 2 1/4 - 7 · х = 1 3/8

х : 9/4 - 7х = 11/8

х · 4/9 - 7х = 11/8

-6 5/9х = 11/8

-59/9х = 11/8

х = 11/8 : (-59/9)

х = 11/8 · (-9/59)

х = -99/472

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Проверка:

-99/472 : 2 1/4 - 7 · (-99/472) = 1 3/8

-99/472 · 4/9 + 693/472 = 1 3/8

-44/472 + 693/472 = 1 3/8

649/472 = 1 3/8

1,375 = 1,375 - верно