I believe you understand questions one and two - complementary angles are angles that add to ninety degrees. For the third question, you have the first couple steps correct. After you subtract 36 from both sides, you are left with . Next: ÷ because you have , so this will give you the value of a single - the answer is nine. So, . Hope this helps! If you have any questions or need me to explain anything, feel free to ask :)