Katie is comparing the prices of packages of paper cups. One brand costs c dollars and contains 80 cups per package. Another brand costs d dollars and contains 100 cups per package. Which expression cannot be used to find the difference in the cost of 1 paper cup between the two brands? A. begin mathsize 18px style 100 d minus 80 c end style B. begin mathsize 18px style open parentheses c divided by 80 close parentheses minus open parentheses d divided by 100 close parentheses end style
C. begin mathsize 18px style 1 over 80 c minus 1 over 100 d end style D. begin mathsize 18px style c over 80 minus d over 100 end style