Write the system in the vector matrix form Ax=b and solve by finding A^-1

Vector Matrix form?

[2,1;4,3]*[x;y] = [2,-4]

2x+y=2

4x+3x=-4

So A^-1 =

[1.5,-.5;-2,1]

So I don't understand what I am suppose to do with the A^-1. I understand how to use ref, rref and Cramer's rule to solve these equations but I am not understanding what method they are wanting me to use.

Reference: Answer is x=5, y=-8