If the problem is asking how tall the attic is then what you do is add the known measurements for the the other stories which are 8 1/2 ft and add that to 8 5/6 ft which gives you 17 1/3. And you know the overall height of the house is 24 1/3. So simply subtract 17 1/3 from 24 1/3 to get the height of your attic which is 7 feet.