Bài `1:`

`1) 121-(118-x)=217`

`=> 118-x=121-217`

`=> 118-x=-96`

`=> x=118+96`

`=> x=214`

Vậy `x=214`

`2) [(6x-39):7].4=12`

`=> (6x-39):7=12:4`

`=> (6x-39):7=3`

`=> 6x-39=3.7`

`=> 6x-39=21`

`=> 6x=21+39`

`=> 6x=60`

`=> x=60:6`

`=> x=10`

Vậy `x=10`

`3) 3x-24.73=2.74`

`=> 3x-1752=148`

`=> 3x=148+1752`

`=> 3x=1900`

`=> x=1900/3`

 Vậy `x=1900/3`

`6) 7x-x=5^21:5^19+3.22-7`

`=> 6x=5^2+66-7`

`=> 6x=25+66-7`

`=> 6x=84`

`=> x=84:6`

`=> x=14`

Vậy `x=14`

`7) 70-5.(x-3)=5^2`

`=> 70-5.(x-3)=25`

`=> 5.(x-3)=70-25`

`=> 5.(x-3)=45`

`=> x-3=45:5`

`=> x-3=9`

`=> x=9+3`

`=> x=12`

Vậy `x=12`

`8) 12x-33=3^2 . 3^3`

`=> 12x-33=3^5`

`=> 12x-33=243`

`=> 12x=243+33`

`=> 12x=276`

`=> x=276:12`

`=> x=23`

Vậy `x=23`