The answer is D. I am sure of this. Brainpower? Have a great day!
Diameter is 2r, or 18.8 ft
Circumference is 2*pi*r, or 59.1 ft
6 math books would be 126
5 English books would be 150
126+150=276
To find f(-20), first figure out which piece x = -20 fits with.
Since -20 < -12, x = -20 first in the domain used by the third piece.
For f(-20), treat this function as if it was just f(x) = 3x-7.
f(-20) = 3(-20) -7
= -60 - 7
= -67
