Supplementary angles are angles that add up to 180 degrees, aka one straight line. The supplementary angles here are:
1 and 2, 1 and 3, 2 and 4, 3 and 4, 5 and 6, 6 and 8, 7 and 8, and 6 and 7. Well, those are the more obvious ones. 1 and 7 are supplementary because if you envision them next to each other, you’ll see that they create a straight line. So, with that logic, 3 and 5 are supplementary because when you put them together, they create a straight line
That'd be 20(p-3). Check by multiplying out 20(p-3)
