PR=SQ\dfrac{P}{R}=\dfrac{S}{Q}RP=QS
PS=RQ\dfrac{P}{S}=\dfrac{R}{Q}SP=QR
PQ=RS\dfrac{P}{Q}=\dfrac{R}{S}QP=SR
PQ=SR\dfrac{P}{Q}=\dfrac{S}{R}QP=RS