If I would have been twice as efficient as today, I would have finished work in 12 days. If my efficiency is reduced to one-third of what it is at present, in how many days, I would be able to finish the work?

Question: If I would have been twice as efficient as today, I would have finished work in 12 days. If my efficiency is reduced to one-third of what it is at present, in how many days, I would be able to finish the work?

Solution:
Let I finish work in x days.
With double efficiency, the time taken = x/2 days
That means when the efficiency was double (2x),
then the time taken to finish the work is 12 days
Now,
with the present efficiency time taken to complete the work = 12 × 2 =24 days
With one-third efficiency, the days required to finish the work = 3 × 24 = 72 days,
as efficiency is inversely proportional to days.
Hence, when the efficiency gets one-third, then the work will be finished in 72 days.