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`a, 2/3 + 1/3 : 3x = 20%`

`⇒2/3 + 1/x = 1/5`

`⇒1/x = -7/15`

`⇒x = -15/7`

`b, [3-x]/[5-x] = 6/11`

`⇒11(3-x) = 6(5-x)`

`⇒33 - 11x =30 - 6x`

`⇒5x = 3`

`⇒ x = 3/5`

`c, 29/30 - (13/23 + x) =  7/69`

`⇒277/690 - x = 7/69`

`⇒x = 3/10`

`d, 1/2x - 2/3 x = 7/12`

`⇒ -1/6x = 7/12`

`⇒x = 7/12 . (-6) = -7/2`

`e, ( 1 1/3 - 29% x - 5/12) - 2x = 1,6 : 3/5`

`⇒(4/3 - 29/100 x - 5/12) - 2x - 8/3 = 0`

`⇒-29/100 x - 7/4 = 0`

`⇒x = -7/4 : 29/100 = 175/29`

`f, 1/2 (x - 2/3) - 1/3 (2x - 3) = x`

`⇒1/2 x - 1/3 - 2/3 x + 1 - x = 0`

`⇒ - 7/6x +2/3 = 0`

`⇒-7/6 x = -2/3`

`⇒x = 4/7`

`g, 2(1/2 - x) - 3(x-1/3) = 7/2`

`⇒1 - 2x - 3x + 1 = 7/2`

`⇒-5x = 3/2`

`⇒x = -3/10`