Please help me with question 21, and only 21!!!! I know the rest!!! I also know that b is 75 and d is 46 cause they're opposite. Just please explain what a and c are, how you know, and what kind of angles; such as corresponding, opposite, adjacent, supplementary, etc. Again, that is question 21, and I need help with angle a and c!!! please answer asap, I really need to know this!