Pipe A can fill a tank in 12 minutes and pipe B cam empty it in 24 minutes. If both the pipes are opened together after how many minutes should pipe B be closed, so that the tank is filled in 30 minutes?  Choose the correct choice from the following answers: A) 18 B) 27 C) 98 D) 27 E) 36
Let the pipe B be closed after x minutes.   30/12 - x/24 = 1 =&gt; x/24 = 30/12 - 1 = 3/2   =&gt; x = 3/2 * 24= 
<gadget id="calculator">3/2 * 24</gadget>
<output>36</output>
36.   Answer:36
<result>E</result>
Pipe A can fill a tank in 12 minutes and pipe B cam empty it in 24 minutes. If both the pipes are opened together after how many minutes should pipe B be closed, so that the tank is filled in 30 minutes?