A can do a work in 10days and B can do the same work in 8 days. They work together for 3days and then A goes away. In how many days will B finish the work?  Choices.
A) 11/17days	B) 21/40days	C) 31/40days	D) 14/21days	E) 15/31days
A+B can do the work in 3 days = 3( 1/10 + 1/8) = 9/40   Rest of the work = 1 - 9/40 = 31/40   B will do the rest of the work in = 1 - 9/40 = 31/40days   Answer is 31/40days
<result>C</result>
A can do a work in 10days and B can do the same work in 8 days. They work together for 3days and then A goes away. In how many days will B finish the work?