Assume that A is a matrix with three rows. Find the matrix B such that BA gives the matrix resulting from A after the given row operations are performed.
$9 R_{2}\Rightarrow R_{2}$
$5 R_{1}+ R_{3}\Rightarrow R_{3}$
$B =$ $\left[\Rule{0pt}{3.6em}{0pt}\right.$$\left]\Rule{0pt}{3.6em}{0pt}\right.$