A seller bought three different types of mobile covers, C1, C2, and C3. The ratio of their selling prices was 3:4:5. He made a profit of 25% on C1, 10% on C2, but incurred a loss of 20% on C3. What was his approximate percent gain or loss in 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?