if a lends rs . 2000 to b at 15 % per annum and b lends the same sum to c at 17 % per annum then the gain of b in a period of 4 years is ?
"( 2000 * 2 * 4 ) / 100 = > 160 answer : d"
subtract(divide(multiply(multiply(2000, 17), 4), const_100), divide(multiply(multiply(2000, 15), 4), const_100))