`a,`
`( 3x - 1 ) (-1/2 x + 5 ) = 0`
`⇒3x-1=0`
`⇒3x=1`
`⇒x=1/3`
`hoặc`
`(-1/2 x + 5 ) = 0`
`⇒-1/2x=-5`
`⇒x=10`
`b,`
`-2/3 - 1/3 ( 2x - 5 ) = 3/2`
`⇒ - 1/3 ( 2x - 5 ) = -2/3 - 3/2`
`⇒ - 1/3 ( 2x - 5 ) = -13/6`
`⇒2x - 5 = -13/6 : -1/3`
`⇒2x-5=13/2`
`⇒2x=13/2 +5`
`⇒2x=23/2`
`⇒x=23/4`
`c,`
`x-12/4 = 1/2`
`⇒x=1/2 + 12/4`
`⇒x=7/2`