A copy machine, working at a constant rate, makes 40 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ? Choose the most appropriate option
A) 90
B) 2,700
C) 4,500
D) 5,400
E) 2,850
Together the two machines make 40+55= 
<gadget id="calculator">40+55</gadget>
<output>95</output>
95 copies per minute. So, in half an hour they will make 95*30=2,850 copies.   Answer: 2,850.
<result>E</result>
A copy machine, working at a constant rate, makes 40 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?