A trader sells two articles at the same selling price. On one, he makes a 10% profit, and on the other, he incurs a 10% loss. What is his overall profit or loss percentage on the entire transaction?

A company considers hiring an extra machine for $150 per day to produce additional units. If the additional throughput contribution generated from producing these units on the machine is $390, by how much will total profit increase?

If the cost price of an article is 85 times its selling price, what is the loss percentage?