Ta có :
194 - ( 3.x - 9.17 ) + 8 = 30
=> ( 3.x - 9.17 ) + 8 = 194 - 30 = 164
3.x - 153 = 164 - 8 = 156
3.x = 156 + 153
3.x = 309
=> x = 309 : 3
x = 103
Đ/s : 103
194-(3.x-9.17)+8=30
=> 194-(3x-9.17)=22
=> 3x-9.17=194-22
=> 3x-9.17=172
=> 3x-9=172:17
=> 3x-9=172/17
=> 3x =172/17+9
=> 3x=325/17
=> x=325/17:3
=> x=325/51