Amit invested an amount into two parts in the ratio of 4 : 3 on compound interest for two years at the rates of 20% & 15% respectively. If he exchanges rate of interests, then he will get Rs. 705 less interest than earlier interest, then find how much Simple interest he will get, if he invests total amount at the rate of 10 % for two years?

Let parts be 4x and 3x. At 20% and 15% CI for 2 years: Interest1 = 4x(1.2²-1) = 4x(0.44) = 1.76x. Interest2 = 3x(1.15²-1) = 3x(0.3225) = 0.9675x. Total = 2.7275x. If swapped: Interest1' = 4x(1.15²-1) = 4x(0.3225) = 1.29x. Interest2' = 3x(1.2²-1) = 3x(0.44) = 1.32x. Total' = 2.61x. Difference: 2.7275x - 2.61x = 0.1175x = 705. So x = 705/0.1175 = 6000. Total = 7x = 42000. SI at 10% for 2 years = 42000×10%×2 = 8400.