**Riddle**: Farmer Brown came to town with some watermelons. He sold half of them plus half a melon, and found that he had one whole melon left. How many melons did he take to town?

We do not know how many watermelons Farmer Brown originally had. We know that he sold half of his watermelons and another half of a watermelon.

Considering he sold 3 watermelons, a watermelon and half a watermelon, 1.5 watermelons, is half of 3. It makes a total of 2 watermelons with half of the watermelon he sold. When 2 of the 3 watermelons are sold, all that remains is one watermelon, which proves Farmer Brown took three watermelons to town. The answer of this riddle is three melons.

Answer: Three melons!