Seven machines at a certain factory operate at the same constant rate. If six of these machines, operating simultaneously, take 35 hours to fill a certain production order, how many fewer hours does it take all seven machines, operating simultaneously, to fill the same production order?	Choose the correct choice from the following options:
A) 4	B) 5	C) 7	D) 10	E) 12
The total work is 6*35= 
<gadget id="calculator">6*35</gadget>
<output>210</output>
210 machine hours   The time required for seven machines is 210/7= 
<gadget id="calculator">210/7</gadget>
<output>30</output>
30 hours, thus 5 fewer hours.   The answer is 5.
<result>B</result>
Seven machines at a certain factory operate at the same constant rate. If six of these machines, operating simultaneously, take 35 hours to fill a certain production order, how many fewer hours does it take all seven machines, operating simultaneously, to fill the same production order?