12 persons can complete the work in 18 days. After working for 6 days, 4 more persons added to complete the work fast.In how many days they will complete the work?	Choose the correct choice from the following answers.
A) 10	B) 15	C) 17	D) 5	E) 9
Total work=12*18= 
<gadget id="calculator">12*18</gadget>
<output>216</output>
216 units.   After 6 days, work finished=6*12= 
<gadget id="calculator">6*12</gadget>
<output>72</output>
72 units.   Remaining units=216-72= 
<gadget id="calculator">216-72</gadget>
<output>144</output>
144 units.   Remaining days=144/(2+4)=9 days   The option is 9
<result>E</result>
12 persons can complete the work in 18 days. After working for 6 days, 4 more persons added to complete the work fast.In how many days they will complete the work?