72) Find the rate at which the money becomes 5 times in 20 years at simple interest

73) Find the amount received by Suresh on Rupees 7,800 at simple interest for four years at 6.5% per annum

74) Find the market price of a T-shirt if it is sold for Rs. 2546 after allowing a discount of 5%

75) A discount series of 15% and 20 % is equal to a single discount of

76) On selling a calculator for Rs. 371, a man gains 6%. For how much should he sell it to gain 8%?