8/15 + 6/x = 1
X = 12 6/7days
A can do a piece of work in 15 days. When he had worked for 2 days B joins him. If the complete work was finished in 8 days. In how many days B alone can finish the work?
a: 11 6/7days
b: 12 6/7days
c: 13 6/7days
d: 14 6/7days
e: 15 6/7days