Inverse of 4x4 matrix (Casio fx-570/991 EX)

Calculate the inverse of 4 by 4 matrix using Casio fx-570EX or 991EX calculator.
1. Direct method (obtain answer directly from calculator)
2. Indirect method (by finding cofactor of each entry): cofactor of 4x4 matrix = determinant of 3x3 matrix

Manual way of finding 4x4 matrix:
1. Transpose
2. Adjoint
3. Determinant
4. Inverse