8 men working for 9 hours a day complete a piece of work in 20 days. In how many days can 7 men working for 10 hours a day complete the same piece of work?

A and  B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in-

A shopkeeper sells a watch set on discount of 8% of printed price and gain 25 %. If marked price was Rs. 20,000 then, what was the cost price?

A sells a good to B at a profit of 20% and B sells it to C at a profit of 25%. If  C pays Rs. 225 for it, what was the cost price of A?

A man sells a table at 12 % loss and a book at 19% profit then he earns Rs. 160 as profit. But if he sells the table at 12 % profit and the book at 16% loss then he bears a loss of Rs. 40. Find the price of one book?

Some amount out of Rs.7000 was lent at 6% per annum and the remaining at 4% per annum. If the total simple interest from both the fractions in 5 year was Rs.1600, find the sum lent at 6% per annum.

Rs.4000 becomes Rs. 5000 in 4 years at a certain rate of compound interest. What will be the sum at the end of 12 years?

A sum is to be paid back in 3 equal annual instalments. The interest is compound annually at 30% per annum. If each instalment be Rs.21970 then what is the sum?