a) `11/12 . x + 3/4 = -1/6`
`=> 11/12 . x = -1/6 - 3/4`
`=> 11/12 x =-11/12`
`=> x= -11/12 : 11/12`
`=> x=-1`
Vậy `x= -1`
b) `3 - ( 1/6 - x) . 2/3 = 2/3`
`=> (1/6 -x) . 2/3 = 3 - 2/3`
`=> (1/6 -x) . 2/3 = 9/3 - 2/3`
`=> (1/6 -x) . 2/3 = 7/3`
`=> 1/6 -x = 7/3 : 2/3`
`=> 1/6 - x= 7/3 . 3/2`
`=> 1/6 -x =7/2`
`=> x = 1/6 - 7/2`
`=> x = 1/6 - 21/6`
`=> x=-10/3`
Vậy `x = -10/3`
