if the operation € is defined for all x and y by the equation x € y = 2 * x * y , then 9 € ( 4 € 5 ) =
"working inside out , ( 4 € 5 ) = 2 * 4 * 5 = 40 9 € 40 = 2 * 9 * 40 = 720 hence , answer is b"
multiply(multiply(2, 9), multiply(multiply(2, 4), 5))