A = [ 2 1 ]
[ 5 3 ]
C = [ 2 ]
X = [x1 ]
Matrix equation: AX = C so therefore X = A-1C.
Now all you have to do is to calculate the inverse of square matrix A, and multiply it by the columnar matrix C.
The procedure for inverting a square 2-D matrix is easy if done on paper, and is even easier if you let a graphing calculator do it.