The 2 rooms only add up to 45,000 square feet (150 x 150 x 2) and the larger room is only 40,000 square feet (200 x 200) so this only gives you 85,000 square feet (40,000 + 45,000) which is not enough for the 100,000.
Eighths and their multiples are common fractions which I recommend memorizing, but to actually solve this, you use the literal meaning of a fraction and divide 5 by 8. See the long-division below (it was surprisingly difficult to type, so I hope it helps!).
To round 0.625 to the nearest hundredth, we go to the second decimal place, which is 5, so we round up to 0.63.
7.28 is the answer sorry if i’m wrong