A sum of money at a certain rate per annum of simple interest doubles in the 5 years and at a different rate becomes three times in 12 years. The lower rate of interest per annum is

Three men do as much work as 4 boys do and the 4 boys can together complete work in 21 days. In how many days will 9 men and 2 boys complete the same work?

Mr. A bought a laptop with \(16 {{2} \over 3}\) % discount on the labeled price. Had he bought it with 25% discount, he would have saved Rs 600. At what price did he buy the laptop?

5 men, 6 women and 4 children can complete a work in 10 days. 6 women and 6 children can do it in 20 days, while 2 men and 6 women can do it in 18 days. In how many days will 2 men and 1 woman will complete the same work?