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 B leaves after 2 days and C leaves after 4 days from the beginning. How long will work lost?	Choose the correct choice.
A) 3 2/3	B) 5 2/3	C) 6 2/3	D) 4 2/3	E) 7 2/3
x/10 + 2/15 + 4/20 = 1   x = 40/60*10 = 6 2/3   Answer: 6 2/3
<result>C</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 B leaves after 2 days and C leaves after 4 days from the beginning. How long will work lost?