If the operation € is defined for all x and y by the equation x € y = 2*x*y, then 8 € (4 € 5) =  Choose the correct answer:  A) 80  B) 120  C) 160  D) 640  E) 760
working inside out,   (4 € 5) = 2*4*5= 
<gadget id="calculator">2*4*5</gadget>
<output>40</output>
40   8 € 40= 2*8*40= 
<gadget id="calculator">2*8*40</gadget>
<output>640</output>
640   Hence, answer is 640
<result>D</result>
If the operation € is defined for all x and y by the equation x € y = 2*x*y, then 8 € (4 € 5) =