A shopkeeper normally makes a profit of 20% in a certain transaction; he weighs 900 g instead of 1 kg, due to an issue with the weighing machine. If he charges 10% less than what he normally charges, what is his actual profit or loss percentage?

20%

                 CP                 SP

Cost           5                   6

Quantity   1000            900

          ————————————

               50        :          54

if he charge 10% less means 90% of 50 = 45

Then the profit % = 54 - 45 = 9 × \(\frac{100}{45}\) = 20%