A can do a work in 12 days. B can do the same work in 24 days. If both A & B are working together in how many days they will finish the work? Choose the correct choice from the following choices.
A) 3  B) 5  C) 8  D) 2  E) 6

Rationale: "a rate = 1 / 12 b rate = 1 / 24 ( a + b ) rate = ( 1 / 12 ) + ( 1 / 24 ) = 1 / 8 a & b finish the work in 8 days correct option is c"
Answer: C