John and ismail donated some money to the relief fund. the amount paid by ismail is rs85 more than twice that of john. if the total money paid by them is rs4000, then find the amount of money donated by john.

850 persons went to see a circus-show. Each adult paid Rs 25 and each child. Paid Rs 10 for the admission ticket, Find the number of adults and number of children, if the total collection from them amounts to Rs 17500.

Rahul's father wants to deposit some amount of money every year on the day of Rahul's birthday. On his 1^(st) birthday Rs.100, on his birthday Rs.300, on his 3^(rd) birthday Rs.600, on his birthday Rs.1000 and so on. What is the amount deposited by his father on Rahul's 15^(th) birthday?

Yadaiah for his family needs borrowed Rs 5120 at 12(1)/(2)% per annum compounded annually. How much amount he has to pay to clear the debt at the end of two year nine months? Also find total how much interest he has paid?