need this to be shown by hand

2-240. Compute the 4x4 matrix defined by A-B+C where A, B and C are given by 0.856 0.328 0.0663 0.908 1.142 0.438 0.0884 1.211 0.529 0.426 0.364 0.434 0.705 0.568 0.485 0.579 A 0.675 1.083 0.534 0.183 0.506 0.812 0.400 0.137 0.869 0.535 0.368 1.326 0.652 0.402 0.0276 0.995