A can do a piece of work in 4 hours . A and C together can do it in just 2 hours, while B and C together need 3 hours to finish the same work. B alone can complete the work in --- hours.  Options: A) 65 B) 85 C) 48 D) 12 E) 25

Rationale: explanation : work done by a in 1 hour = 1 / 4 work done by b and c in 1 hour = 1 / 3 work done by a and c in 1 hour = 1 / 2 work done by a , b and c in 1 hour = 1 / 4 + 1 / 3 = 7 / 12 work done by b in 1 hour = 7 / 12 – 1 / 2 = 1 / 12 = > b alone can complete the work in 12 hours answer : d
Answer: D