if the operation € is defined for all x and y by the equation x € y = 2 * x * y , then 7 € ( 4 € 5 ) =
"working inside out , ( 4 € 5 ) = 2 * 4 * 5 = 40 7 € 40 = 2 * 3 * 40 = 560 hence , answer is e"
multiply(multiply(2, 7), multiply(multiply(2, 4), 5))