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.

If the least common multiple of two numbers, 1728 and K is 5184, then how many values of K are possible? 

Meetali and Neeraj got married 30 years ago. Meetali is 4 years younger than Neeraj. When they got married the difference between 2 times of the Meetali's age and 1.5 times of the Neeraj's age was 5 years. Find the present age of Meetali and Neeraj.

The area of trapezium is 21 square cm, the distance between the parallel sides is 3 cm and one of the parallel sides is 8.3 cm. What is the length of the other parallel side ?

Study the following graph to answer these questions :
Percent profit earned by two companies A & B over the years.
Profit = Income – Expenditure

Expenditure of Company B in 1999 was 90% of its expenditure in 1998. Income of Company B in 1999 was what percent of its income in 1998?