Twice the difference between two numbers is equal to their sum. If one number is 15, find the other number.

An article is sold for Rs 4,777 after giving a discount of 15%. What is the marked price of the article?

The vertices of the 1 cm side are cut from each corner of a square with a side of 4.5 cm. Find the circumference and area of the octagon formed?

A man spends $$ {2\over3}rd$$ of his income. If his income increases by 14 % and the expenditure increases by 20%, then the percentage increase in his savings will be

If there are four lines in a plane, then what cannot be the number of points of intersection of these lines? 

The largest and the second largest angles of a triangle are in the ratio of 3 : 2 respectively. The smallest angle is 20% of the sum of the rest two angles. What is the sum of the smallest and the second largest angles?

Bobby and Billy can complete a job in 28 days and 20 days, respectively. They work together for 5 days, after which Billy leaves the job. In how many days did Bobby alone complete the rest of the job?

If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is?