Answer:
answer: c 138°
Step-by-step explanation:
because one of the angles is 42° this means that B is also 42° because opposite angles are equal
to find out the remaining A and C angles we do
360-42-42=276
because opposite angles here are equal again we just divide 276 by 2 to get angles A and C
276÷2= 138°
so the answer is: C 138°