Albert completes a piece of work in 20 days, Rose completes the same work in 30 days. If both of them work together, then the number of days required to complete the work is?  Choose one.
A) 10 B) 12 C) 15 D) 20 E) 18
If A can complete a work in x days and B can complete the same work in y days, then, both   of them together can complete the work in x y/ x+ y days.   That is, the required No. of days = 20 × 30/50 = 12 days   Answer is 12
<result>B</result>
Albert completes a piece of work in 20 days, Rose completes the same work in 30 days. If both of them work together, then the number of days required to complete the work is?