A tank can supply water to a village for 30 days. If a leak at the bottom of the tank drains out 15 liters per day, the supply lasts for 20 days only. For how many days will the supply last if the leak drains out 20 liters per day?
Options:
A) 12  B) 14  C) 15  D) 16  E) 18
Losing 15 liters per day results in a loss of 300 liters in 20 days. So, those 300 liters were for 10 days, making daily consumption of the village 30 liters per day. Thus the capacity of the tank is  30*30= 
<gadget id="calculator"> 30*30</gadget>
<output>900</output>
900 liters.   Losing 20 liters plus 30 liters gives 50 liters per day. At this rate the supply will last   900/50= 
<gadget id="calculator">  900/50</gadget>
<output>18</output>
18 days.   The answer is 18.
<result>E</result>
A tank can supply water to a village for 30 days. If a leak at the bottom of the tank drains out 15 liters per day, the supply lasts for 20 days only. For how many days will the supply last if the leak drains out 20 liters per day?