When an article is sold at a 15% loss by a shopkeeper, if he had sold it for Rs. 525 more, he would have earned a profit of 20%. Find the cost price of the article (in Rs.).

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?