Molly can do a task in 15 days while Sandy can do the task in 30 days. How many days will it take to complete the task if both work together?  Answers
A) 8  B) 10  C) 11  D) 12  E) 14
Each day, Molly can do 1/15 of the task.   Each day, Sandy can do 1/30 of the task.   Each day, they can do 1/15 + 1/30 = 1/10 of the task.   The task will be completed in 10 days.   The answer is 10.
<result>B</result>
Molly can do a task in 15 days while Sandy can do the task in 30 days. How many days will it take to complete the task if both work together?