if a lends rs . 4000 to b at 10 % per annum and b lends the same sum to c at 11.5 % per annum then the gain of b in a period of 3 years is ?
"( 4000 * 1.5 * 3 ) / 100 = > 180 answer : e"
subtract(divide(multiply(multiply(4000, 11.5), 3), const_100), divide(multiply(multiply(4000, 10), 3), const_100))