The probability of something is the answer you're looking for (i.e. that fits the criteria) divided by total possible answers.
You're looking for those opposed, which is 292.
The total possible is 262, since there's 626 total students in the survey.
Hence, P(opposed) = 292/626.
It is appropriate to leave it as a fraction and reduce it, or divide and get a decimal number. Your instructor may prefer a specific format for the answer, and for rounding decimals.