Answer:
part A you have correct.
is there a 'D" for part B? A through C answers don't seem correct.
after a response from the poster, "D" was the correct answer.
re-posting it because some random person deleted it.
Answer:
amt. the shop spends on 40 pairs
= $11 × 40
= $440
amt. paid extra (due to fixed cost) per pair
= ($450 - $440) ÷ 40
= $0.25
amt. per pair to break even
= $11 + $0.25
= $11.25
Since the second angle + first angle is 90 degrees, the third angle must be 90 degrees to complete the 180 degrees in a circle.
Hope this helps!