X alone can do a piece of work in 15 days and Y alone can do it in 10 days. X and Y undertook to do it for Rs. 720. With the help of Z they finished it in 5 days. How much is paid to Z?	Select:	A) Rs 100	B) Rs 110	C) Rs 120	D) Rs 130	E) Rs 140
(X+Y+Z)'s one day work=1/5 and (X+Y)'s one day work=1/15+1/10..   Z's one day work=1/30. ratio of one day work=1/15:1/10:1/30=2:3:1   therefore z will be paid=1/6*720= 
<gadget id="calculator">1/6*720</gadget>
<output>120</output>
Rs 120.   ANSWER:Rs 120
<result>C</result>
X alone can do a piece of work in 15 days and Y alone can do it in 10 days. X and Y undertook to do it for Rs. 720. With the help of Z they finished it in 5 days. How much is paid to Z?