A and B can do a work in 12 days and 36 days respectively. If they work on alternate days beginning with B, in how many days will the work be completed?	Choose the correct choice from the following answers:
A) 11  B) 17  C) 10  D) 17  E) 18
The work done in the first two days = 1/12 + 1/36 = 1/9   so, 9 such two days are required to finish the work.   i.e., 18 days are required to finish the work.   Answer: 18
<result>E</result>
A and B can do a work in 12 days and 36 days respectively. If they work on alternate days beginning with B, in how many days will the work be completed?