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\(\left\{\begin{matrix}7x-4y=50\\-6x+7y=-25\end{matrix}\right.\)

\(\left\{\begin{matrix}7x-4y=50\\-6x+7y=-25\end{matrix}\right.\\ \Leftrightarrow \left\{\begin{array}{c|c|c}7x-4y=50& \color{red}{6.} & \color{blue}{7.} \\-6x+7y=-25& \color{red}{7.} & \color{blue}{4.} \end{array}\right.\\ \Leftrightarrow \left\{\begin{matrix} \color{red}{\underline{42x-42x}-24y+49y=300-175} \\ \color{blue}{49x-24x\underline{-28y+28y}=350-100} \end{matrix}\right.\\ \Leftrightarrow \left\{\begin{matrix}25y=125 \\25x=250\end{matrix}\right.\\ \Leftrightarrow \left\{\begin{matrix}y=\frac{125}{25}=5 \\x=\frac{250}{25}=10\end{matrix}\right.\\ \qquad V=\{(10,5)\}\)