#### Answer

4 minutes.

#### Work Step by Step

First, we find how many copies copier A made in the initial time:
copies $ = 40(6) = 240$
This means that there are 520-240=280 copies left to be made. Thus:
$280 = 40t + 30t \\ t = 4$

Published by
Cengage Learning

ISBN 10:
1285194055

ISBN 13:
978-1-28519-405-9

4 minutes.

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