Answer:
There are more than one way to do this:
Here's one way:
The least common multiple of 4 people and 3 people is 12 people.
12 people is 3 times as many people as 4 people, and
12 people is 4 times as many as 3 people.
Since 4 people take 6 days, 3 times as many people take only
one-third as long, or only 2 days. (since 2 is one-third of 6)
Since 3 people is only one-fourth as many people as 12, it will take
them 4 times as long as it would take 12 people, or 8 days. (since
4 times 2 is 8).
Explanation:
subtract 8 from 12
4 days