A cistern has a leak which would empty the cistern in 20 minutes. A tap is turned on which admits 4 liters a minute into the cistern, and it is emptied in 24 minutes. How many liters does the cistern hold? Choose the correct choice from the following.
A) 480
B) 289
C) 279
D) 276
E) 911
1/x - 1/20 = -1/24   x = 120   120 * 4= 
<gadget id="calculator">120 * 4</gadget>
<output>480</output>
480   480nswer:480
<result>A</result>
A cistern has a leak which would empty the cistern in 20 minutes. A tap is turned on which admits 4 liters a minute into the cistern, and it is emptied in 24 minutes. How many liters does the cistern hold?