Hello!
To first solve this problem, let's look at how much the workers would've finished when they were still a group.
Since the job could've been originally done in 11 days with 7 people, and they only worked for 3 days (with 7 people), they originally finished 3/11 of the job.
Now, let's look at how much each person finishes of the job in one day.
Since 7 workers can finish the job in 11 days, this means that 1 worker can finish the job in 77 days, translating to that one worker does 1/77 of the job in one day.
Let's connect these ideas. There is 8/11 of the project remaining, and this was finished in 14 days. This means, every day, 4/77 of the project was finished. (8/11 divided by 14)
Since we know one worker does 1/77 of the job per day, and every day, 4/77 of the job was finished, 4 workers were on the team.
Therefore, 7-4, 3 workers left the team.
Hope this helped!
