if 2 x = 3 y = 20 , then 12 xy = ?
"2 x = 20 ; x = 10 3 y = 20 ; y = 20 / 3 multiply : 12 xy = 12 * 10 * 20 / 3 = 800 . answer : b ."
divide(subtract(divide(multiply(2, const_100), const_2), const_2), add(divide(multiply(2, const_100), const_2), const_2))