a)In how much time will simple interest on a sum of money be 2/5th of the sum, at the rate of 10% per annum b) At what rate of
interest will simple interest be half the principal in 5 years. c)A sum of money amounts to Rs. 1265 in 3 years and to Rs.1430 in 6 years, at simple interest. Find the sum and the rate percent.