So, to answer your question, Y= C. 68°.
Since the sum of a triangle's three sides has to add up to 180°, I looked and checked what numbers would make the equation work. 112° is too high, and 44° and 56° were too low. 68° works because 68-12 is 56, 56+56 is 112, and 112+ 68 adds up to 180.
