Profit and Loss - General Questions

A dishonest dealer professes to sell his goods at cost price but uses a weight of 875 g for a kilogram. What is his gain percent?

The cost price of 20 articles is equal to the selling price of 19 articles. What is the gain percent?

A man sells two articles at the same price. On one he gains 20% and on the other he loses 20%. What is his overall gain or loss percent?

A dishonest dealer professes to sell his goods at cost price but uses a weight of 800 g for a kilogram. What is his gain percent?

A man sells two articles at the same price. On one he gains 10% and on the other he loses 10%. What is his overall gain or loss percent?