Working at their respective constant rates, machine A makes 100 copies in 15 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?
Choose the correct choice from the following options:
A) 250 B) 425 C) 650 D) 700 E) 750
Machine A can produce 100 *30/15= 
<gadget id="calculator">100 *30/15</gadget>
<output>200</output>
200 copies   And, Machine B can produce   150* 30/10= 
<gadget id="calculator">  150* 30/10</gadget>
<output>450</output>
450 Copies   Total producing 650 Copies.   650 is the answer
<result>C</result>
Working at their respective constant rates, machine A makes 100 copies in 15 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?