if a lends rs . 3500 to b at 10 % per annum and b lends the same sum to c at 12 % per annum then the gain of b in a period of 3 years is ?
( 3500 * 2 * 3 ) / 100 = > 210 answer : b
subtract(divide(multiply(multiply(3500, 12), const_3), const_100), divide(multiply(multiply(3500, 10), 3), const_100))