`a, x + 1/2 = ( - 3 )/4`
`⇔ x = ( - 3 )/4 - 1/2`
`⇔ x = ( - 5 )/4`
Vậy `, x = ( - 5 )/4 .`
`b, 1,5 + 1 1/4 . x = 2/3`
`⇔ 3/2 + 5/4 . x = 2/3`
`⇔ 5/4 . x = 2/3 - 3/2`
`⇔ 5/4 . x = ( - 5 )/6`
`⇔ x = ( - 5 )/6 : 5/4`
`⇔ x = ( - 2 )/3`
Vậy `, x = ( - 2 )/3 .`
`c, x - 25% . x = 1/2`
`⇔ x . 1 - 1/4 . x = 1/2`
`⇔ x . ( 1 - 1/4 ) = 1/2`
`⇔ x . 3/4 = 1/2`
`⇔ x = 1/2 : 3/4`
`⇔ x = 2/3`
Vậy `, x = 2/3 .`