Looking at this chart:
. . . it is not hard to see the Perfect 5ths (remembering always that a Perfect 5th is made of three whole steps plus a half step).
DO to SOL
. . . is a P5
RE to LA
. . . is a P5
FA to DO
. . . is a P5
DO to MI would
NOT
be a P5
MI to TI
. . . is a P5
FA to LA would
NOT
be a P5
