Question

if 8 men can dig a well in 18 days , in how days 12 men dig the same well

Answer 1

5.3 days
as per my calculations

Answer 2

FULL ANSWER WITH STEPS

Time taken by 8 men to dig a well = 18 days

Time taken by 1 man to dig a well = (18 × 8) days = 144 days
Here, instead of multiplication, I performed division, because if 1 man does the work, then the workload will be more. 

Now,
Time taken by 12 men to dig a well = (144 ÷ 12) days = 12 days
Here, instead of multiplication, I performed division, because, instead of 1 man, if 12 men will do the whole work together, then the workload will reduce, and the work will be done much faster. 

∴ In 12 days, 12 men can dig up the same well. 

Hope this may help you. 

If you have any doubt, then you can ask me in the comments.