Answer: I brought fewer apples than John.
Explanation: Fewer is used when discussing countable things. In this case, you are comparing apples.
Answer: I have less work to do Today.
Explanation: Less is used got singular mass nouns.
Answer: I have less money then I would like.
Explanation: We are talking about money, but not exactly dollars so you can fewer dollars, but less money so the answer is less.
Answer: There are fewer girls than boys.
Answer: I have less chores to do Tomorrow.
Answer: To lose weight, eat fewer calories.
Answer: I have less homework Today.
Answer: Do we need more eggs or fewer?
Answer: When I am a senior, I will take fewer classes.
Answer: I would like to carry less weight in my backpack.
