Answer:
30 workers are required.
Step-by-step explanation:
If the site measured 30 acres and was completed in 10 days, then it can be said that on average
were made.
Then, 24 workers completed 3 acres / day.
Then,

8 workers can complete 1 acre per day
Now to know how many workers are needed to complete 45 acres in 12 days, we multiply:
.
Finally, 30 workers are required.
To solve this problem it was assumed that everyone worked at the same pace, which may not be true, the fact that some work at a slower or faster pace than another could alter the result, causing them to finish less or more acres by day.