X does a work in 20 days. Y does the same work in 30 days. In how many days they together will do the same work?	Choose the most appropriate option:
A) 10	B) 12	C) 20	D) 30	E) 15
X's 1day's work= 1/20   Y's 1 day's work=1/30   (X+Y)'s 1day's work= (1/20+1/30)=1/12   both together will finish the work in 12 days.   correct option is 12
<result>B</result>
X does a work in 20 days. Y does the same work in 30 days. In how many days they together will do the same work?