The marked price of an article is ₹ 500 and is sold for ₹ 400; the discount given is :

1. 10%

2. 20%

3. 25%

4. none of these

Given:

M.P. of an article = ₹ 500

S.P. of article = ₹ 400

Discount = M.P. - S.P.

= ₹ 500 - ₹ 400

= ₹ 100

$\text{Discount\%} = \dfrac{\text{Discount}}{\text{M.P.}}\times 100\%\\[1em] = \dfrac{100}{500}\times 100\%\\[1em] = \dfrac{1}{5}\times 100\%\\[1em] = \dfrac{100}{5}\%\\[1em] = 20\%$

Hence,option 2 is the correct option.