Answer

`a, 2 . (x - 1/2) = 1/3`

`=> (x - 1/2) = 1/3 : 2`

`=> x - 1/2 = 1/6`

`=> x = 1/6 + 1/2`

`=> x = 2/3`

Vậy `x = 2/3`

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`b, 4/5 - |x - 1/2| = 3/4`

`=> |x - 1/2| = 4/5 - 3/4`

`=> |x - 1/2| = 1/20`

`=>` $\left[\begin{matrix} x - \dfrac{1}{2} = \dfrac{1}{20}\\ x - \dfrac{1}{2} = \dfrac{-1}{20}\end{matrix}\right.$

`=>` $\left[\begin{matrix} x = \dfrac{1}{20} + \dfrac{1}{2}\\ x = \dfrac{-1}{20} + \dfrac{1}{2}\end{matrix}\right.$

`=>` $\left[\begin{matrix} x = \dfrac{11}{20}\\ x = \dfrac{9}{20}\end{matrix}\right.$

Vậy `x \in {11/20 ; 9/20}`

`a) 2(x - 1/2) = 1/3`

`=> x - 1/2 = 1/3 : 2`

`=> x -1/2 = 1/6`

`=> x = 1/6 + 1/2`

`=> x =  2/3`

Vậy `x = 2/3`

`b) 4/5 - | x - 1/2 | = 3/4`

`=> |x - 1/2| = 4/5 - 3/4`

`=> |x- 1/2| = 1/20`

`=> x - 1/2 = 1/20` hoặc `x - 1/2 = -1/20`

`=> x = 1/20 + 1/2`        `x = (-1/20) + 1/2`

`=> x = 11/20`                `x = 9/20`

Vậy `x = 11/20` hoặc `x = 9/20`