Profit and Loss - General Questions

A man sells two articles at the same price. On one he gains 12% and on the other he loses 12%. What is his overall gain or loss percent?

A dishonest dealer professes to sell his goods at cost price but uses a weight of 850 g for a kilogram. What is his gain percent?

An article bought for Rs. 300 is sold for Rs. 420. What is the gain percent?

A shopkeeper marks his goods 20% above the cost price and allows a discount of 15%. 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?