Total cost price of two watches is Rs.6000 and selling price of each is equal. 1st is sold at 15% loss and 2nd is sold at 19% profit. Find the cost price of watch which is sold at 15% loss.

Rs.3500/-

             C.P.            :         S.P.

1st :         20            :          17        ........(i)      [15% = \(\frac{3}{20}\)]

2nd:         100          :         119                         [19% = \(\frac{19}{100}\)]

ATQ, (S.P. is same), therefore multiple (i) by 7

                C.P.            :         S.P.

1st :         140            :          119      

2nd:         100            :          119

               240 (total C.P.)

⇒ 240R = 6000 (given)

⇒ 1R    = 25

Hence,

C.P. of 1st article = 140R = 140 × 25 = Rs.3500/-