A can do a piece of work in 10 days and B can do it in 15 days and C can do it 20 days. They started the work together and A leaves after 5 days and B leaves after 3 days from the beginning. How long will work lost?  Pick:	A) 2	B) 4	C) 5	D) 6	E) 7
5/10 + 3/15 + x/20 = 1   x = 18/3= 
<gadget id="calculator">18/3</gadget>
<output>6</output>
6   Answer: 6
<result>D</result>
A can do a piece of work in 10 days and B can do it in 15 days and C can do it 20 days. They started the work together and A leaves after 5 days and B leaves after 3 days from the beginning. How long will work lost?