I had this question recently in an online exam that really confused me (it's not hard).
A business decided to recycle all their old paper cups and produce new ones from the recycled cardboard. For every new cup it would require $6$ used cups. They have $551$ used cups, how many new cups can be created?
I thought easy, divide $551$ by $6$ thus allowing the business to create $91$ new cups.
The answer was (according to the creator) $110$. Which is $551$ divided by $5$. I still can't wrap my head around the logic, I have written the question as I was given it, could anyone please help me shed some light on this?