algebra
posted by Tom on .
Tad was delivering lunch to a local office building. His first delivery was to the middle floor of the building. He then took th elevator up 4 floors for the next delivery, down 6 floors for his third delivery, and up 7 floors for his final delivery. He was then on the top floor of the building. How many floors were in this building?

x+46+7= 5
5+5=10