B lives in an even numbered flat on lowermost floor i.e. B lives on floor ground floor in flat 2. Z lives in an even numbered flat on floor number 2. B and C live on same floor. P lives immediately above C and the numbers of their flats is same. So, Now, C either lives immediate west or east of B which means P either lives in flat 3 or flat 1. So, we have two possibilities. Case I: When C and P live on flat – 3: 
Case-2 When C and P live on Flat-1 
R and A live on same floor. X lives to the immediate west of R. R lives immediately below the vacant flat and the flat number of vacant flat and R is same. A lives in flat –1. There is one floor between R and Q. Now, R lives immediately below vacant flat so, the vacant flat must be in topmost floor. Case I: When C and P live on flat – 3: 
Case II: When C and P live on flat – 1 
D lives somewhere above Y in same flat number, but not on flat 3. Now, we cannot fix D and Y in same flat number in case II, so, case II is invalid. The final arrangement is as follows: 
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