Find A - B
A = [ 3 7 8 ]
7 9 3
7 9 9
B = [ 2 2 6 ]
6 7 8
5 8 6
eh? just subtract corresponding elements:
[1 5 2]
...
A = [ 3 7 8 ]
7 9 3
7 9 9
B = [ 2 2 6 ]
6 7 8
5 8 6
[1 5 2]
...