Five machines at a certain factory operate at the same constant rate. If four of these machines, operating simultaneously, take 45 hours to fill a certain production order, how many fewer hours does it take all five machines, operating simultaneously, to fill the same production order? Choose the correct choice:
A) 3
B) 5
C) 6
D) 16
E) 9
Total work = 4*45 machine hrs   Time taken = 4* 45 /5= 
<gadget id="calculator">4* 45 /5</gadget>
<output>36</output>
&gt; 36 hours...   Thus all five machines, operating simultaneously will take ( 45 - 36 ) 9 hours..   Answer will be (9) 9
<result>E</result>
Five machines at a certain factory operate at the same constant rate. If four of these machines, operating simultaneously, take 45 hours to fill a certain production order, how many fewer hours does it take all five machines, operating simultaneously, to fill the same production order?