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 left (y - x) to (y + x) is -

$$\eqalign{ & {\text{Let C}}{\text{.P}}{\text{. of the article be Rs}}.p. \cr & Then, \cr & x = 85\% {\text{ of Rs}}{\text{. }}p = {\text{Rs}}.\frac{{85}}{{100}}p. \cr & {\text{and,}} \cr & y = 115\% {\text{ of Rs}}{\text{. }}p = {\text{Rs}}.\frac{{115}}{{100}}p. \cr & \therefore \left( {y - x} \right):\left( {y + x} \right) \cr & = \left( {\frac{{115}}{{100}}p - \frac{{85}}{{100}}p} \right):\left( {\frac{{115}}{{100}}p + \frac{{85}}{{100}}p} \right) \cr & = \frac{{30}}{{100}}p:\frac{{200}}{{100}}p \cr & = \frac{3}{{10}}:2 \cr & = 3:20 \cr} $$