`a) 50%x - 1/3x = -2`
`=> 1/2x - 1/3x = -2`
`=> (1/2 - 1/3)x = -2`
`=> 1/6x = -2`
`=> x = -2 : 1/6`
`=> x = -2 . 6`
`=> x = -12`
Vậy `x = -12`
`b) 3 1/7 - (2 1/7 - 1 1/5) + 2|1-3x| = 4 + 20%`
`=> 3 1/7 - 2 1/7 + 1 1/5 + 2|1-3x| = 4 + 20%`
`=> 1 + 1 1/5 + 2|1-3x| = 4 + 20%`
`=> 2 + 1/5 + 2|1-3x| = 4 + 1/5`
`=> 2|1-3x| = 4 + 1/5 - 2 + 1/5`
`=> 2|1-3x| = 2`
`=> |1-3x| = 1`
Xét `1-3x = 1`
`=> 3x = 0`
`=> x = 0`
Xét `1-3x = -1`
`=> 3x = 2`
`=> x = 2/3`
Vậy `x = 0` hoặc `x = 2/3`
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