Question

Two pipes A and B can fill a cistern in 10 and 15 minutes
respectively, but an empty pipe C can empty it in 5 minutes. The
pipes A and B are kept open for 4 minutes and the emptying pipe
C also opened. In what time is the cistern emptied?
(a) 10 minutes (b) 16 minutes (c) 20 minutes (d) 22 minutes,
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Answer 1

Step-by-step explanation:

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