An article is marked at ₹ 800 and is sold at 20% discount. Its S.P. is :

1. ₹ 160

2. ₹ 960

3. ₹ 640

4. ₹ 780

Given:

M.P. = ₹ 800

Discount % = 20%

$\text{Discount\%} = \dfrac{\text{Discount}}{\text{M.P.}} \times 100$

Putting the values, we get

$\Rightarrow\ 20 = \dfrac{\text{Discount}}{800} \times 100\\[1em] \Rightarrow\ \text{Discount} = \dfrac{20 \times 800}{100}\\[1em] = \dfrac{16000}{100}\\[1em] = 160$

And we know,

$\text{Discount} = \text{M.P. - S.P}$

Putting the values,we get

$160 = 800 - \text{S.P}\\[1em] \Rightarrow \text{S.P.} = 800 - 160\\[1em] \Rightarrow \text{S.P.} = 640$

Hence, option 3 is the correct option.