A can do a job in 9 days. B can do the job in 6 days and C can do the job in 3/4 the time required for both A and B. A and B work together for 2 days; then C completes the job. How long did C work?
(a) 2 days
(b) 2 2/5 days
(c) 2 1/5 days
(d) 3 1/5 days
NOTE: Some readers have suggested that none of these answers are correct (surprise!), but have not yet proposed a better answer with appropriate justification. Why not be the first?
Source: ARCO's Practice for the Army Test, 1942, p. 40