Ram, who is half as efficient as Krish, will take 18 days to complete a task if he worked alone. If Ram and Krish worked together, how long will they take to complete the task?  Choose one:
A) 16 days
B) 12 days
C) 8 days
D) 6 days
E) 18 days

Rationale: "number of days taken by ram to complete task = 18 since ram is half as efficient as krish , amount of work done by krish in 1 day = amount of work done by ram in 2 days if total work done by ram in 18 days is 18 w amount of work done by ram in 1 day = w amount of work done by krish in 1 day = 2 w total amount of work done by krish and ram in a day = 3 w total amount of time needed by krish and ram to complete task = 18 w / 3 w = 6 days answer d"
Answer: D