ta có \(\frac{x}{8}=\frac{y}{-5}\)
\(\frac{x}{8}=\frac{-4x}{8\cdot\left(-4\right)}=\frac{4x}{32}\)
\(\frac{y}{-5}=\frac{3y}{-5.3}=\frac{3y}{-15}\)
mà \(\frac{x}{8}=\frac{y}{5}=>-\frac{4x}{32}=\frac{3y}{-15}\)
áp dụng tính chất dãy tỉ số bằng nhau ta có
\(-\frac{4x}{32}=\frac{3y}{-15}=-\frac{4x-3y}{32-\left(-15\right)=}-\frac{136}{47}\)
*\(\frac{x}{8}=-\frac{136}{47}=>x=-\frac{1088}{47}\)
*\(\frac{y}{-5}=\frac{-136}{47}=>y=\frac{680}{47}\)
\(\frac{x}{8}=\frac{y}{-5}\)\(\Rightarrow\frac{4x}{32}=\frac{3y}{-15}=\frac{4x+3y}{32-15}=\frac{-\left(-4x-3y\right)}{17}=\frac{-\left(-136\right)}{17}=\frac{136}{7}\)
\(\frac{x}{8}=\frac{136}{17}\Rightarrow17.x=136.8=1088\Rightarrow x=\frac{1088}{17}\)
\(\frac{y}{-5}=\frac{136}{17}\Rightarrow17y=136.\left(-5\right)=-680\Rightarrow y=-\frac{680}{17}\)