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
- - - - - - - - - - - - - - - - - - - - - - - - - - - -
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
