Peter bought an item at 20% discount on its original price. He sold it with 40% increase on the price he bought it. The new sale price is greater than the original price (in percent) by: 

18 percent of the coal was destroyed in a coal mine. If only 492 tons of coal was received, then tell how much coal was destroyed?

In an examination, 93 % of students passed and 259 failed. The total number of students appearing at the examination was: 

If the radius of a circle is decreased by 50%, its area is reduced by

Some students (only boys and girls) from different schools1 appeared for an Olympiad exam. 20% of the boys and 15% of the girls failed the exam. The number of boys who passed the exam was 70 more than that of the girls who passed the exam'. A total of 90 students failed. Find the number of students that appeared for the exam.

The population of a city is 48,600. If there is a 25% increase in the first year and a reduction of 8% in the second year, then what will be the population of this city at the end of 2 years?

A man saves 20% of his  monthly salary. If an account of dearness of things he is to increase his monthly expenses by 20%, he is only able to save Rs. 200 per month. What is his monthly salary?

60% boys are failed in History and 65% boys are failed in Geography while total 30% boys are failed in both the subjects. If total 1200 boys appeared in the examination then total how many boys are passed?