If an article is sold for Rs. x, there is a loss of 15%. If the same article is sold for Rs. y, there is a profit of 15%. The ratio of (y - x) to (y + x) is

Initial selling price = Rs. $$x$$

Cost price after 15% loss = $$\frac{x}{100-15}\times100$$ --------------(i)

New selling price = Rs. $$y$$

Cost price after 15% gain = $$\frac{y}{100+15}\times100$$ -------------(ii)

Comparing equations (i) and (ii),

=> $$\frac{x}{85}=\frac{y}{115}$$

=> $$\frac{x}{y}=\frac{115}{85}=\frac{23}{17}$$

Using componendo and dividendo

=> $$\frac{y-x}{y+x}=\frac{17-23}{17+23}=\frac{6}{40}$$

=> $$\frac{y-x}{y+x}=3:20$$

=> Ans - (C)