A is twice as fast as B. If B alone can do a piece of work in 10 days, in what time can A and B together complete the work?	Choose the correct choice from the following:
A) 10 / 3  B) 8  C) 9  D) 7 / 3  E) 12

Rationale: "a can do the work in 10 / 2 i . e . , 5 days . a and b ' s one day ' s work = 1 / 5 + 1 / 10 = ( 2 + 1 ) / 10 = 10 / 3 so a and b together can do the work in 10 / 3 days . answer : a"
Answer: A