A good answer might be:
<0001 0110 (correct)
The number to be subtracted is negated by the
usual means (reflect the bits, add one):
0001 1011 ==> 1110 0101
Then the "binary addition algorithm" is used:
11100 001
0011 0001 == 49d
1110 0101 == -27d
--------- -----
0001 0110 22d
Since the carry into the most significant column is the same
as the carry out of that column the result is correct.
(To double check, the numbers were translated into decimal representation.)
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