Question

2y+7x=-5 5y-7x=12

`2y + 7x = - 5 \: \: \\ 5y - 7x = 12`

Answer 1

Answer: x = -1 y = 1

Answer 2

`\begin{cases}2y + 7x = - 5\\5y - 7x = 12\end{cases}`

+______________

`7y=7\ /:7`

`y=1`

`\begin{cases}2y + 7x = - 5\\ y=1\end{cases}`

`\begin{cases}2 \cdot 1 + 7x = - 5\\ y=1\end{cases}`

`\begin{cases}2 + 7x = - 5\\ y=1\end{cases}`

`\begin{cases} 7x = - 5-2\\ y=1\end{cases}`

`\begin{cases}7x = - 7\ /:7\\ y=1\end{cases}`

`\begin{cases}x = - 1\\ y=1\end{cases}`