A dishonest shopkeeper, at the time of selling and purchasing, weighs 10% less and 20% more per kilogram respectively. Find the percentage profit earned by treachery. (Assuming he sells at Cost Price)

Explanation:-

While purchasing he would take 1200 grams for the price of 1000 grams. While selling he would sell 900 grams for the price of 1000 grams.
Since, CP = SP
The profit earned by him,
^{Goods Left}/_{Goods sold} = ^{(300 *100)}/₉₀₀ = 33.33%.