a reduction of 25 % in the price of oil enables a house wife to obtain 5 kgs more for rs . 800 , what is the reduced price for kg ?
"a 800 * ( 25 / 100 ) = 200 - - - - 5 ? - - - - 1 = > rs . 40"
divide(divide(multiply(800, 25), const_100), 5)