if the operation € is defined for all x and y by the equation x € y = 2 * x * y , then 6 € ( 4 € 5 ) =
working inside out , ( 4 € 5 ) = 2 * 4 * 5 = 40 6 € 40 = 2 * 6 * 40 = 480 hence , answer is a
multiply(multiply(2, 6), multiply(multiply(2, 4), 5))