123 - (8х - 11) * 2 = 49
(8х - 11) * 2 = 123 - 49
(8х - 11) * 2 = 74
8х - 11 = 74 : 2
8х -11 = 37
8х = 37 + 11
8х = 48
х = 48 : 8
х = 6
-----------------------------------------
123 - (8 * 6 - 11) * 2 = 49
123 - (48 - 11) * 2 = 49
123 - 37 * 2 = 49
123 - 74 = 49
49 = 49