the tax on a commodity is diminished by 20 % but its consumption is increased by 5 % . find the decrease percent in the revenue derived from it ?
"explanation : 100 * 100 = 10000 80 * 105 = 8400 10000 - - - - - - - 1600 100 - - - - - - - ? = 16 % c )"
subtract(const_100, divide(multiply(add(const_100, 5), subtract(const_100, 20)), const_100))