\(\left[\begin{array}{ccc}1&3&7\\1&1&1\end{array}\right]\)
multiply 2nd row by -1 and add to first row
\(\left[\begin{array}{ccc}0&2&6\\1&1&1\end{array}\right]\)
divide the 1st row by 2
\(\left[\begin{array}{ccc}0&1&3\\1&1&1\end{array}\right]\)
multiply the first row by -1 and add to 2nd row
\(\left[\begin{array}{ccc}0&1&3\\1&0&-2\end{array}\right]\)
now we know
y+3=0
x-2=0
therefor
y=-3
x=2
