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`(3x-10)^3 = (-8)/27`
`<=> (3x-10)^3 = ((-2)/3)^3`
`<=> 3x - 10 = (-2)/3`
`<=> 3x = (-2)/3 + 10`
`<=> 3x = 28/3`
`<=>x = 28/3 : 3`
`<=> x = 28/3 . 1/3`
`<=> x = 28/9`