Find the inverse of the following matrix:

A =
[ 3 4 ]
[ 1 2 ]

I don't know what to do need a bit of help, thanks

det(A) = 6 - 4 = 2

Acof =

[ 2 -1 ]
[ -4 3 ]

Acof ' =

[ 2 -4 ]
[ -1 3 ]

A^-1 =

[ 2 -4 ]
[ -1 3 ]*(1/2)

[ 1 -2 ]
[ -1/2 3/2 ] = A^-1