1. The simple interest on a certain sum at 5% per annum for 3 years and 4 years differ by 82. Find the sum. 2. Rajan's monthly income is 20% more than the monthly income of Sarita. What per cent of Sarita's income is less than Rajan's monthly income? 3. A machine is sold by A to B at a profit of 10% and then B sold it to C at a profit of 20%. If C paid 1200 for the machine, what amount was paid by A to purchase the machine?