If a shop keeper buys almonds at Rs. 250 per kg and sells them at Rs. 10 per 50 g then he

$50gr=?$

$1000x=250\times 50$

$x=\frac{250\times 50}{1000}=\text{Rs}\mathrm{.12.5}$

$\text{loss}=\text{Rs}\text{.12}\text{.5-10}\text{=}\text{Rs}\text{.2}\text{.5}$

$\text{Loss}\%=\frac{2.5}{12.5}\times 100=20\%$

Shop keeper sells almonds per kg-Rs.200

(or)

$\therefore \text{loss\%}=\frac{\text{loss}}{\text{C}\text{.P}}\times 100$

$=\frac{50}{250}\times 100$

$=20\%$