Working simultaneously and independently at an identical constant rate, 30 machines of a certain type can produce a total of x units of product P in 3 days. How many of these machines, working simultaneously and independently at this constant rate, can produce a total of 5x units of product P in 10 days?	Select.
A) 41	B) 44	C) 45	D) 47	E) 50
The rate of 30 machines is rate=job/time=x/3 units per day --&gt; the rate of 1 machine 1/30*(x/3)=x/90 units per day;   Now, again as {time}*{combined rate}={job done}   then 10*(m*x/90)=5x --&gt; m=45.   Answer: 45.
<result>C</result>
Working simultaneously and independently at an identical constant rate, 30 machines of a certain type can produce a total of x units of product P in 3 days. How many of these machines, working simultaneously and independently at this constant rate, can produce a total of 5x units of product P in 10 days?