Aditya sells two wrist watches from his personal collection for Rs. 12,600 each. On the first watch, he gains 26% and, on the second, he loses 10%. Find his overall gain or loss percentage.

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?