A can do a piece of work in 8 days and B alone can do it in 12 days. How much time will both take to finish the work ?  Choose the correct option
A) 4.8 B) 6.333 C) 7.333 D) 8.5 E) 9

Rationale: "this question can be solved by different methods . we need to conserve time in exams so solving this problem using equations is the good idea . time taken to finish the job = xy / ( x + y ) = 8 x 12 / ( 8 + 12 ) = 96 / 20 = 4.8 days answer : a"
Answer: A