can't do math for the life of me. HELP.

MITer94
Sun, 20 Oct 2013 22:58:34 +0000

Sorry, what I mean by “the building has six or seven rooms” is “the building has exactly six or seven rooms.”

The question says that four buildings have more than 8 rooms, and ten buildings (including the aforementioned four) have more than 7 rooms. This should tell you that exactly six buildings have exactly 8 rooms. Once we know this, we can find that there are five buildings with six or seven rooms. Note that we don’t actually know how many buildings have six rooms, or how many have seven, but there are five buildings with six or seven rooms.