A is thrice as good a workman as B and takes 10 days less to do a piece of work than B takes. B alone can do the whole work in Choose the most appropriate option
A) 15 days  B) 10 days  C) 9 days  D) 8 days  E) 7 days

Rationale: explanation : ratio of times taken by a and b = 1 : 3 means b will take 3 times which a will do in 1 time if difference of time is 2 days , b takes 3 days if difference of time is 10 days , b takes ( 3 / 2 ) * 10 = 15 days option a
Answer: A