2x - 23. 33 = 138
2x - 8 . 27 = 138
2x - 216 = 138
2x = 138 + 216
2x = 354
2x = 354 : 2
x = 177
vậy x = 177
( 6x - 34 ) . 73 = 3 . 74
( 6x - 81 ) . 343 = 3 . 2401
( 6x - 81 ) . 343 = 7203
6x - 81 = 7203 : 343
6x - 81 = 21
6x = 21 + 81
6x = 102
x = 102 : 6
x = 17
vậy x = 17