A can complete \(1 \over 3\) of a work in 7 days and B can complete \(2 \over 7\) of the same work in 10 days. In how many days can both A and B together complete the work?
1
\(12{3 \over 8}\)
2
\(11{7 \over 8}\)
3
\(13{1 \over 8}\)
4
\(15{1 \over 7}\)