There are two buildings P and Q. If 35 persons sent from P to Q.............How many persons are there in building in P?

Question

There are two buildings P and Q.
If 35 persons sent from P to Q, then the number of persons in each building is the same.
If 60 persons are sent from Q to P, then the number of persons in P is double the number of persons in Q.
How many persons are there in building in P?

Answer 1

320

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P-35=Q+35 --> (1)
(Q-60)*2=P+60 --> (2)
(1)--> P=Q+70
(2) --> 2Q-120=Q+70+60 --> Q=250 --> P=320