if 2 x = 3 y = 10 , then 15 xy = ?
"2 x = 10 ; x = 5 3 y = 10 ; y = 10 / 3 multiply : 15 xy = 15 * 5 * 10 / 3 = 250 answer : e ."
divide(subtract(divide(multiply(2, const_100), const_2), const_2), add(divide(multiply(2, const_100), const_2), const_2))