mention the question correctly.....it seems something is missing because it is difficult to find out.
-7
Shivangi Sehgal answered this
According to Euclid's axiom, if equals are subtracted from equals then the remainders are equal.
This implies in the case too.
PQ=QR
QX=QY
PQ-QX=QR-QY (Axiom)
=> PX=RY
hence proved.