A boy spends Rs 20 to purchase toffees at Rs 1 each. Next day, he purchased some toffees for Rs 40 with a discount of 50 paise per toffee. What is the average price per toffee (in paise)?
A Sonar of a ship sends sounds waves of speed 1500 m/s. These waves are reflected back by the ocean floor in 5 seconds. Find the depth (in m) of the ocean floor.