The C.P. of two watches taken together is Rs. 840. If by selling one at a profit of 16% and the other at a loss of 12%, there is no loss or gain in the whole transaction, then the C.P. of the two watches are respectively `R s .360 ,\ R s .480` b. `R s .380 ,\ R s .460` c. `R s .480 ,\ R s .360` d. `R s .400 ,\ R s .440`