Answer:
b=9 dollars per kilogram
c=4 dollars per kilogram.
Because + and - make - which makes you left with 3-5 which equals to -2 because it gets negative.
39 inches = 3 feet 3 inches
42.5 inches = 3 feet 6 1/2 inches
61 3/4 inches - 5 feet 1 3/4 inches
The answer to that question is D