Isha can do a certain piece of work in 15 days. Isha and Smriti can together do the same work in 11 days, and Isha, Smriti and Ashlesha can do the same work together in 10days. In how many days can Isha and Ashlesha do the same work?
A64/6
B62/7
C70/5
D66/5