A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 75 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?
Choose the correct answer
A) 90	B) 2,700	C) 3,300	D) 5,400	E) 324,000
Together the two machines make 35+75= 
<gadget id="calculator">35+75</gadget>
<output>110</output>
110 copies per minute. So, in half an hour they will make 110*30=3,300 copies.   Answer: 3,300.
<result>C</result>
A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 75 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?