Hector works on the 4th floor of a high rise building. he needs to go up 9 floors to get to the cafeteria for lunch, and then go down 5 floors to attend a meeting. on what floor does the meeting take place?

So, start at 4. You know that he needs to go up  floors, so it would be 4 + 9, which is 13. 
He is now on the 13th floor. You also know, that he needs to go down 5 floors. So the equation would look like this:
4 + 9 - 5 = ?
so, 13 - 5 is 8.
The meeting is on the 8th floor.

Hope this helps!!
~Kiwi

Not sure what the question is but i hope this x = years100 * x