A man buys two watches ‘A’ and ‘B’ at a total cost of ₹800. He sells both watches at the same selling price, and earns a profit of 18% on watch ‘A’ and incurs a loss of 22% on watch ‘B’. What are the cost prices of the two watches? (two place after decimal).

A = ₹318.37 and B = ₹481.63

We know that,

18% = \(\frac{9}{50}\)

22% = \(\frac{11}{50}\)

CP : SP of watch A = 50 : 59

CP : SP of watch B = 50 : 39

Making SP of both the watches equal

CP : SP of watch A = 50 : 59      --- (1) × 39

CP :  SP of watch B = 50 : 39      --- (2) × 59

Total CP of watch A and B = 50 × 39 + 50 × 59 = 4900

4900 unit = Rs. 800

1 unit = \(\frac{800}{4900}\)

1950 unit = \(\frac{800}{4900}\) × 1950 = 318.37

CP of watch A = 318.37

CP of watch B = 800 - 318.37 = 481.63