Actually there are two logics for this question 11 +12 = 23 where the last digit came to first and the first came to the last. and this logic replies everywhere.that's why 15 +16 = 31 which in inverse gets to be 13. and the second logic is the difference of 20 no.s.
so to ur question there are 2 answers and that are 13 by the fist logic and 112 by the other logic.
112 is the answer
Hope this helps u !!