A. The term "units" refers to the measurements in the original question or problem. When looking at the question, the units we are measuring are dollars/feet.
B. In this case, the f'(x) means we are looking for the cost (in dollars) to drill the next foot down.
C. Since the cost increases the more feet we drill down, the sign of f'(x) is positive.
R=16
J=32
20+40(which is 20×2)=60
20-4=16
16×2=32
To add a mixed number you must first convert it into a heavy headed fraction eg. 12/4
Then you must find a common denominator for all of the fractions like you normally do for regular addition of fractions
After you have added them you must convert the heavy headed fraction back into a mixed number by seeing how many times the numerator goes into the denominator
Answer: The answer to your question is 13.636. I hope this helps you :D
