To do a certain work, the ratio of the efficiencies of A and B is 5 ∶ 11. Working together, they can do the same work in 27\(\frac{1}{2}\) days. A and B work together for 20 days. C alone completes the remaining work in 18 days. C alone can do 75% of the original work in:
1
56\(\frac{1}{2}\) days
2
49\(\frac{1}{2}\) days
3
35 days
4
33 days