Final answer:
The county's annual profit would be $100,000.
Step-by-step explanation:
To calculate the county's annual profit, we need to consider the revenue and the costs. The revenue per prisoner processed is $75. If the county processes 4,000 prisoners per year, the total revenue would be 4,000 x $75 = $300,000.
The cost per prisoner to process the paperwork at the new location is $50. If the county processes 4,000 prisoners per year, the total cost would be 4,000 x $50 = $200,000.
Subtracting the cost from the revenue, the county's annual profit would be $300,000 - $200,000 = $100,000.