tolong djwab ya bserra caranya plis

[tex]\left(\begin{array}{cc}2x&3\\-1&-y\end{array}\right)\left(\begin{array}{cc}-1&3\\5&4\end{array}\right)-\left(\begin{array}{cc}-5y&5\\2&2x\end{array}\right)=\left(\begin{array}{cc}7&1\\9&7\end{array}\right)\\\left(\begin{array}{cc}(15-2x)&(12+6y)\\(1-5y)&(-12-3y)\end{array}\right)=\left(\begin{array}{cc}(7-5y)&6\\11&(7+2x)\end{array}\right)\\\\a_{21}:1-5y=11\rightarrow y=-2\\a_{12}:12+6y=6\rightarrow y=-1[/tex]

karena ada dua nilai y, padahal seharusnya y hanya ada satu, maka tidak ada solusi