3 + х = 5/9,
х = 5/9 - 3,
х = 5/9 - 27/9,
х = - 22/9,
х = -2 4/9,
проверка:
3 + (- 2 4/9) = 5/9,
3 - 2 4/9 = 5/9,
5/9 = 5/9
6 1/12 - х = 2 5/12,
х = 6 1/12 - 2 5/12,
х = 5 13/12 - 2 5/12,
х = (5 - 2) + (13/12 - 5/12),
х = 3 + 8/12,
х = 3 2/3,
проверка:
6 1/12 - 3 2/3 = 2 5/12,
5 13/12 - 3 2/3 = 2 5/12,
(5 - 3) + (13/12 - 8/12) = 2 5/12,
2 + 5/12 = 2 5/12,
2 5/12 = 2 5/12