\(\frac{x+5y}{2x+9y}=\frac{4}{7}\left(y\ne0;2x+9y\ne0\right).\)
\(\Rightarrow\left(x+5y\right).7=\left(2x+9y\right).4\)
\(\Rightarrow7x+35y=8x+36y\)
\(\Rightarrow7x-8x=36y-35y\)
\(\Rightarrow-1x=1y\)
\(\Rightarrow\frac{x}{y}=\frac{1}{-1}\)
Vậy \(\frac{x}{y}=\frac{1}{-1}.\)
Chúc bạn học tốt!