Question

A man and 3 women can do a piece of work in 20 days. if a woman can do 50% of the
work that a man can do. in how many days a woman will do the job alone?​

Answer 1

A man and 3 women do that work in 20 days.

If a man is to be replaced, we need 2 women in order to complete the task in same time. (Here, Women do 50% of a man can do. ) So, now we have 5 women working.

Now, if only one woman works instead of 5, time taken will be 5 times. i.e. 20 days x 5 = 100 Days.