Two men can fill the tank in 5hr and 4hr respectively, while the third empty it in 20hr. If all pipes are opened simultaneously, then the tank will be filled in
Choose the correct choice from the following choices:	A) 2	B) 2.5	C) 3	D) 3.5	E) 3.7
Work done by all the men working together in 1 hour.   1/5+1/4−1/20=8/20   Hence, tank will be filled in 20/8= 
<gadget id="calculator">20/8</gadget>
<output>5/2 = around 2.5</output>
2.5 hour   2.5
<result>B</result>
Two men can fill the tank in 5hr and 4hr respectively, while the third empty it in 20hr. If all pipes are opened simultaneously, then the tank will be filled in