Solve, explain why the algorithm works
3892
-2567

Unfortunately, you don't share enough info here for the question to make sense.

If I assume that you want to subtract 2567 from 3892, I'd write the problem in a slightly different manner:

 3892
-2567


Now subtract.  Borrow 1 from 9 to obtain a 12, and then subtract 7 from 12, obtaining 5.  Result:  1825.  Is this correct?  You could check by adding 1825 to 2567.  You are correct if their sum is 3892.

B is the answer to the problem