\(\left\{{}\begin{matrix}40x+56y=3.04\\58.5x+74.5y=4.15\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{3.04-40x}{56}\\58.5x+74.5y=4.15\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{3.04-40x}{56}\\58.5x+74.5\dfrac{3.04-40x}{56}=4.15\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=0.02\\y=\dfrac{3.04-40\times0.02}{56}=0.04\end{matrix}\right.\)