By how much percentage above the cost price should an article be marked for sale so that after allowing two successive discounts of 20% and 6.25%, a net profit of 20% is made on the cost price?

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?