the tax on a commodity is diminished by 30 % but its consumption is increased by 15 % . find the decrease percent in the revenue derived from it ?
"100 * 100 = 10000 70 * 115 = 8050 10000 - - - - - - - 1950 100 - - - - - - - ? = 20 % answer : a"
subtract(const_100, divide(multiply(add(const_100, 15), subtract(const_100, 30)), const_100))