Answer
$$B=2A_1+A_2.$$
Work Step by Step
Let $$
B=\left[\begin{array}{ccc}{2} & {5} \\ {0} & {3}\end{array}\right], \quad A_1=\left[\begin{array}{ccc}{1} & {2} \\ {-1} & {1}\end{array}\right], \quad A_2=\left[\begin{array}{ccc}{0} & {1} \\ {2} & {1}\end{array}\right]
$$
We have
$$B=aA_1+bA_2=a\left[\begin{array}{ccc}{1} & {2} \\ {-1} & {1}\end{array}\right]+b\left[\begin{array}{ccc}{0} & {1} \\ {2} & {1}\end{array}\right]$$
and hence we get the system $$a=2, \quad 2a+b=5,\quad -a+2b=0, \quad a+b=3.$$
The above system has the solution $a=2$ and $b=1$,
so $$B=2A_1+A_2.$$
