一道数学题 My co-worker asked me a simple mathematical question this afternoon. She said” A and B are going upstairs.They both started on the 1st floor.When A is on the 5th floor, B is on the 3rd floor. My question is which floor will be B on when A will be on the 17th floor?"After 10 mins, I gave her a wrong answer.How dull I am. 谢谢纠错