A does a work in 10 days and B does the same work in 15 days. In how many days they together will do the same work?	Choices:  A) 1  B) 6  C) 7  D) 5  E) 43
A's 1 day work = 1/10; B's 1 day work = 1/15   (A + B)'s 1 day work = (1/10 + 1/15) = 1/6   So, both together will finish the work in 6 days.   Answer: 6
<result>B</result>
A does a work in 10 days and B does the same work in 15 days. In how many days they together will do the same work?