The first odd number before 231 which would be on the same side of the hall is 229. The first odd number after would be 233.
On the odd side of the hall, the order would be room 229, room 231, room 233.
Add 2+6 that gives you x then add 10+30 then add them numbers and divide x by it’s self
I believe it would be 0.08
27+3x-31=20
-4+3x=20
+4 +4
3x=24
X=8