DS Question - machine and rate

If two copying machines work simultaneously at their respective constant rates, how many copies do they produce in 5 minutes?
(1) One of the machines produces copies at the constant rate of 250 copies per minute.
(2) One of the machines produces copies at twice the constant rate of the other machine.

From (1):
It talks about only one machine. We dont know the rate of other machine to determine the answer. So, INSUFFICIENT

From (2):
Rate of machine A = 2 * Rate of machine B
or
Rate of machine B = 2 * Rate of machine A

But again, we dont know the exact rate to determine the answer of how many copies those machines produce. So, INSUFFICIENT


Now from (1) and (2), if both the machines work simultaneously, then in we know the number of copies they produce in one minute which is ( 250(A) + 500(B) ) or ( 500(A) + 250(B) ) = 750

Hence the option I selected was ( C )

But the OA says, ( E ).. Can you please let me know if I am missing something in my logic.