Answer:
C. 16 days
Step-by-step explanation:
Let´s say each worker does 1 ¨work¨, for each day, in order to complete the job in 15 days. That´s a total of 150 work.
If only 6 workers worked for the first 5 days, then we only do 30 by Day 5.
2 more workers join, so they do 8 work each day, 24 work in 3 days, 54 work by Day 8.
4 more workers join to complete the job, so we now do 12 work each day.
150 - 54 = 96
96 work is left to do, which would be done in 8 days by 12 workers.
8 days + 8 days = 16 days
