find the inverse of the matrix if it exists.

Answer:
A
First calculate the determinant:
3*9 - (-2)*(-10)=27-20=7
determinant isn't 0 so we can find inverse
swap top left and bottom right then negate the other two:
9 2
10 3
divide whole thing by 1/determinant:
1/7 * [9 2]
[10 3]