If a can complete a work in x days and b can complete a work in y days. In how many days that they will work together simultaneously?  Choose the correct choice.
A) xy/(x+y)	B) (x+y)/xy	C) 1/xy	D) xy	E) x+y
xy/(x+y)'s one day work=1/x   B's one day work=1/y   a+b=1/x+1/y=(x+y)/xy(for one day)   Total days=xy/(x+y)   xy/(x+y)nswer is option xy/(x+y)
<result>A</result>
If a can complete a work in x days and b can complete a work in y days. In how many days that they will work together simultaneously?