Final answer:
The number of extra cases of chicken fingers is calculated by the formula (C × F)/P, representing the cases per person times the number of fewer people who showed up.
Step-by-step explanation:
The question involves finding out how many extra cases of chicken fingers will be left if F fewer people show up than expected at a party. The student originally planned to buy C cases to feed P people. If F people did not show up, then the number of extra cases can be calculated by taking the cases per person (C/P) and multiplying it by the number of people who did not show up (F), which would be (C/P) × F. Since C/P represents the cases needed for one person, multiplying this by F gives us the total cases for F people. Hence, the correct formula is (C/P) × F, simplified to (C × F)/P.