The simple and compound interest that can be earned in two years at the same rate is Rs 1,000 and Rs 1,040 respectively. What is the rate (percent per annum) of interest?
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)?