(84 : (х - 4) + 8) * 8 - 19 = 141
(84 : (х - 4) + 8) * 8 = 141 + 19
(84 : (х - 4) + 8) * 8 = 160
84 : (х - 4) + 8 = 160 : 8
84 : (х - 4) + 8 = 20
84 : (х - 4) = 20 - 8
84 : (х - 4) = 12
х - 4 = 84 : 12
х - 4 = 7
х = 7 + 4
х = 11
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Проверка: (84 : (11- 4) + 8) * 8 - 19 = 141
(84 : 7 + 8) * 8 - 19 = 141
(12 + 8) * 8 - 19 = 141
20 * 8 - 19 = 141
160 - 19 = 141
141 = 141