Em tách từng ý ra hỏi em nhé
\(\begin{array}{l}
a)\,\dfrac{{1 + 2y}}{{18}} = \dfrac{{1 + 4y}}{{24}} = \dfrac{{2\left( {1 + 2y} \right) - \left( {1 + 4y} \right)}}{{18.2 - 24}} = \dfrac{1}{{12}}\\
\Rightarrow 12\left( {1 + 2y} \right) = 18 \Rightarrow 24y = 6 \Leftrightarrow y = \dfrac{1}{4}\\
\Rightarrow \dfrac{{1 + 6.\dfrac{1}{4}}}{{6x}} = \dfrac{1}{{12}} \Rightarrow 6x = 30 \Leftrightarrow x = 5\\
b)\,\dfrac{{5y + 2}}{{5x}} = \dfrac{{7y + 3}}{{4x}} \Rightarrow \dfrac{{5y + 2}}{5} = \dfrac{{7y + 3}}{4} = \dfrac{{7\left( {5y + 2} \right) - 5\left( {7y + 3} \right)}}{{7.5 - 5.4}} = - \dfrac{1}{{15}}\\
\Rightarrow - 15\left( {5y + 2} \right) = 5 \Leftrightarrow - 75y = 45 \Rightarrow y = -\dfrac{3}{5}\\
\Rightarrow \dfrac{{3.\dfrac{-3}{5} + 1}}{{12}} = \dfrac{{5.\dfrac{-3}{5} + 2}}{{5x}} \Leftrightarrow \dfrac{-1}{{5x}} = \dfrac{-1}{{15}} \Rightarrow x = 3
\end{array}\)
