Which of the following statements are correct?

A. A man purchased an item at \(\frac{4}{5}\) of its selling price `X', and sold it at 5% more than 'X'. His gain is 25%.

B. A dealer professes to sell his goods at cost price but uses a weight of 900 g for a kg weight. His gain is 11\(\frac{1}{9}\)%.

C. If loss is one third of the selling price, the loss percentage is 25%.

D. By selling 100 pens, a vendor gains the selling price of 20 pens. His gain is 20%.

Choose the correct answer from the options given below: