Answer:
C and $320.45
Step-by-step explanation:
I think it's C because this is the full function :

And to get the b part of the question i just put the number in

I'm not a 100% sure, sorry if it's wrong
Answer:
366
Step-by-step explanation:
2×3+4×100-50+10
PEMDAS says multiply and divide from left to right
6 + 400 - 50 +10
Then add and subtract
406-50+10
356+10
366
Circumference = pi * diameter = 21 * 22/7 = 66 m (answer)