The math teacher bought 20 APPLES and CUT THE APPLES.
HOW MANY APPLE DO WE HAVE?
In general, the answer will be 40. It is because we Multiply 20 by 2.
In fact, (this is just my opinion) there is really no specific answer for this because the question is not explained well. This is the questions that confused my mind on answering your question.
1. HOW MANY APPLES OUT OF 20 DID THE TEACHER CUT? DID HE/SHE CUT ALL?
2. HOW MANY CUTS/SLICES DID THE TEACHER MADE ON A SINGLE APPLE.
If this is logic (I always do logic! Sorry) this is going to be the answers:
1. 0 APPLES. Because the math teacher is just assuming.
2. BILLIONS OF APPLES. "How many apples do we have?"