Ravi purchases 90 pens and sells 40 pens at a gain of 10% and 50 pens at a gain of 20%. Had he sold all of them at a uniform profit of 15% he would have got Rs. 40 less. Find the cost price of each pen.

Mrs. Deepa Devi saves 30% of her salary. If she receives Rs.42,000 per month as her salary, what is her monthly expenditure?

Cost of two articles were in the ratio of 16: 23. The cost of first article increases by 10% and that of second by Rs.477. Now the costs of two articles are in the ratio of 11: 20. The price of the second article (in Rs.) in the beginning was-

A merchant marks his goods at Rs. 900 and allows a discount of 25%. If he still gain 12.5%, then the cost price of the article is

In a test consisting of 150 questions carrying 1 mark each, Saurabh answered 80 % of the first 75 question correctly. What percent of the other 75 question does he need to answer correctly to score 60 % overall? 

Natasha decided to spend 45% of her salary on shopping. On completion of her shopping, she realized that she had spent only Rs.11475, which was 60% of what she had decided to spent. How much is Natasha’s salary?