Answer:
Step-by-step explanation:
(x^2+8x+8)+(-10x^2+5x) = (x^2-10x^2) + (8x+5x) + 8
= -x^2 +13x + 8
A (-5, 6)
B (-5, 2)
C (-9, 2)
D (-9, 6)
As it is just a rotation around the origin by 180, you can just change the sign in front of the numbers :)
BE is parallel to CD, therefore, m∠BEC=m∠ECD, therefore mBC=mDE
BE is the diameter, so Arc BE is 180 degree
mBC+mCD+mDE=180
replace mCD with 3mBC, and replace mDE with mBC: mBC+3mBC+mBC=180
5mBC=180
mBC=180/5=36
mCD=3mBC=3*36=108
the inscirbed angle m∠ECD= the measure of arc DE=36

That's 7.68% = 7.7% (rounded)
Note: C(5, 4) is the number of combinations of 5 things taken 4 at a time. You may have seen this written as

In general,