There are three foam generators in the factory, each of the first two can generate 12 liters of foam in one hour and the third can generate 18 liters in an hour. The three generators start working together at the same time and after one hour and a half one of the first generators stops working and two hours after that the third generator stops working and only one generator is left. If 5 hours after they all started to work the last generator stops working, how many liters of foam were generated?	Answers.
A) 120. B) 132. C) 141 D) 154. E) 166.
Let the foam generators capacity be -   A = 12 lit/hr   B = 12 lit/hr   C = 18 lit/hr   Total foam generation in 1 hour will be 42 lit ( 12 + 12 + 18 ) ; since in 1 and 1/2 hr they will generate   42 + 21= 
<gadget id="calculator">  42 + 21</gadget>
<output>63</output>
&gt; 63 litres...   Now one of the first generators stops working ( Say A stops working ) , so we have -   B= 12 lit/hr   C = 18 lit/hr   Total foam generation in 2 hour will be 60 litres {2 (12+18)}   The third generator stops working and now only B works for the remaining time 1 and 1/2 ( 5 - 1 and 1/2 - 2 )...   Foam generated by B will be  3/2 * 12= 
<gadget id="calculator"> 3/2 * 12</gadget>
<output>18</output>
&gt; 18 litres   So, total foam generated will be 141 Litres ( 63 + 60 + 18 ) ; hence answer will be (141)
<result>C</result>
There are three foam generators in the factory, each of the first two can generate 12 liters of foam in one hour and the third can generate 18 liters in an hour. The three generators start working together at the same time and after one hour and a half one of the first generators stops working and two hours after that the third generator stops working and only one generator is left. If 5 hours after they all started to work the last generator stops working, how many liters of foam were generated?