I don't really understand your question. If you're trying to ask what % of people are opposed and what % are not, that is what I will answer here:
Answer:
98% oppose, and 2% are in favor.
Explanation:
Opposed: 245/250 = 0.98
Therefore, 98% of people oppose the new tax.
In favor: (250 - 245)/250 = 5/250 = 0.02
Therefore, 2% of people are in favor of the new tax.