A alone can complete a work in 12 days. Efficiency of B is 20% more than the efficiency of A while efficiency of C is 25% less than the efficiency of B. Altogether, they can complete the 80% of work in∶
1
\(3\frac{3}{{31}}\) days
2
\(5\frac{3}{{31}}\) days
3
\(2\frac{2}{{31}}\) days
4
\(7\frac{1}{{31}}\)days