`x-y=-4<=>x=y-4`
`=>(x-7)/(y+5)=(y-4-7)/(y+5)=(y-11)/(y+5)`
`=>(y-11)/(y+5)=7/6`
`=>6(y-11)=7(y+5)`
`=>6y-66=7y+35`
`=>y=-101`
`=>x=y-4=-105`
Vậy `(x,y)=(-105,-101)`
Làm gì có sao đâu mà vote 5* :))
\(\dfrac{x-7}{y+5}=\dfrac{7}{6}\)
\(\Leftrightarrow\dfrac{x-7}{7}=\dfrac{y+5}{6}=\dfrac{x-7-y-5}{7-6}=\dfrac{-4-12}{1}=-16\)
\(\Leftrightarrow\left\{{}\begin{matrix}x-7=7\cdot\left(-16\right)\\y+5=6\cdot\left(-16\right)\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-105\\y=-101\end{matrix}\right.\)
\(\dfrac{x-7}{5+y}=\dfrac{7}{6}\)
\(\Rightarrow\) \(6.\left(x-7\right)=7.\left(5+y\right)=6x-42=35+7y\)
\(\Rightarrow\) \(6x-7y=35+42=77\)
Mà \(x=y-4\)
Vậy, ta có: \(6y-24-7y=-y-24=77\)
\(\Rightarrow-y=77+24=101\)
\(\Rightarrow y=-101\)
\(\Rightarrow x=-101+\left(-4\right)=-105\)
