Answer:
Let x be the number of watermelons the farmer needs to sell to earn at least $200.
The amount of money earned from selling x watermelons is 8x dollars.
After paying $50 to rent the booth, the farmer's profit is 8x - 50 dollars.
The problem states that the farmer wants to earn at least $200, so we can set up the following inequality:
8x - 50 ≥ 200
Adding 50 to both sides, we get:
8x ≥ 250
Dividing both sides by 8, we get:
x ≥ 31.25
Since the number of watermelons must be a whole number, the farmer needs to sell at least 32 watermelons to earn at least $200 after paying for the booth.