3 1/6 - (× + 11/12) = 1/4
х + 11/12 = 3 1/6 - 1/4
× + 11/12 = 3 2/12 - 3/12
× + 11/12 = 2 14/12 - 3/12
× + 11/12 = 2 11/12
× = 2 11/12 - 11/12
× = 2
6 5/27 - (х - 1 2/9) = 3 20/81
× - 1 2/9 = 6 5/27 - 3 20/81
× - 1 2/9 = 6 10/81 - 3 20/81
× - 1 2/9 = 5 91/81 - 3 20/81
× - 1 2/9 = 2 71/81
× = 1 2/9 + 2 71/81
× = 1 18/81 + 2 71/81
х = 3 89/81 = 4 8/81
3 5/36 -( 1 4/9 - х) = 1 17/18
1 14/9 - х = 3 5/36 - 1 17/18
1 14/9 - х = 3 5/36 - 1 34/36
1 14/9 - х = 2 41/36 - 1 34/36
1 14/9 - х = 1 7/36
х = 1 14/9 - 1 7/36
х = 1 56/36 - 1 7/36
× = 49/36 = 1 13/36
P.S. я не уверена на счет 3 примера)