Explanation:

Correct option:1 

Solution:

10% of 15400 = 1540
20% of 15400 = 3080
Using allegation method

1540            3080

          2080

1000      :        540

Ratio of cost price of S tables and 9 chairs = 1000x : 540x

1000x + 540x = 1540x

1540x = 15400

x = 15400/1540

x = 10

Cost price of 9 chairs = 540 x 10 = 5400

Cost price of 1 chair = 5400/9 = 600

A Cost price of 3 chairs = 3 x 600 = 1800