Đáp án:
`a,`
`3/4x - 1/4 = 2 (x -3) + 1/4`
`⇔ 3/4x - 1/4 = 2x - 6 + 1/4`
`⇔ 3/4x - 1/4 = 2x - 23/4`
`⇔ 3/4x - 1/4 - 2x + 23/4 = 0`
`⇔ (3/4x - 2x) + (-1/4 + 23/4) = 0`
`⇔ -5/4x + 11/2 = 0`
`⇔ -5/4 = 0 - 11/2`
`⇔ -5/4 = -11/2`
`⇔ x = -11/2 : (-5/4)`
`⇔ x = 22/5`
`text{Vậy}` `x = 22/5`
`b,`
`30%x - x + 5/6 = 49/2`
`⇔ (30% - 1)x = 49/2 - 5/6`
`⇔ -7/10x = 71/3`
`⇔ x = 71/3 : (-7/10)`
`⇔ x = -710/21`
`text{Vậy}` `x= (-710)/21`
