Worker A takes 8 hours to do a job. Worker B takes 6 hours to do the same job. How long it take both A & B, working together but independently, to do the same job?  Options
A) 20 / 9
B) 40 / 9
C) 50 / 9
D) 24 / 7
E) 80 / 9

Rationale: "one day work of a = 1 / 8 one day work of b = 1 / 6 so one day work of a and b together = 1 / 8 + 1 / 6 = 7 / 24 so total days required = 24 / 7 answer : d"
Answer: D