[tex]A\left[\begin{array}{ccc}1&0&5\\0&-5&7\\0&3&-4\end{array}\right][/tex]
[tex]B\left[\begin{array}{ccc}3&-5&3\\2&3&1\\4&1&-3\end{array}\right][/tex]
[tex]Now,\\\\2B-A\\\\2\left[\begin{array}{ccc}3&-5&3\\2&3&1\\4&1&-3\end{array}\right]-\left[\begin{array}{ccc}1&0&5\\0&-5&7\\0&3&-4\end{array}\right]\\\\=\left[\begin{array}{ccc}6&-10&6\\4&6&2\\8&2&-6\end{array}\right] -\left[\begin{array}{ccc}1&0&5\\0&-5&7\\0&3&-4\end{array}\right]\\\\=\left[\begin{array}{ccc}5&-10&1\\4&11&-5\\8&-1&-2\end{array}\right][/tex]
Row 1 column 2(a12)=-10
Hence,-10 is your answer.
