2 câu trả lời
`(3x-6)/20 = (5x-9)/30 `
`=> 30(3x - 6) = 20(5x - 9)`
`=> 90x - 180 = 100x - 180`
`=> 90x - 100x = -180 + 180`
`=> -10x = 0`
`=> x = 0`
Vậy `x = 0`
#andy
\[\begin{array}{l}
\dfrac{{3x - 6}}{{20}} = \dfrac{{5x - 9}}{{30}}\\
\Leftrightarrow \dfrac{{3\left( {3x - 6} \right)}}{{20.3}} = \dfrac{{2\left( {5x - 9} \right)}}{{30.2}}\\
\Leftrightarrow \dfrac{{9x - 18}}{{60}} = \dfrac{{10x - 18}}{{60}}\\
\Leftrightarrow 9x - 18 = 10x - 18\\
\Leftrightarrow 9x - 10x = - 18 + 18\\
\Leftrightarrow - x = 0\\
\Leftrightarrow x = 0
\end{array}\]
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