Three out of four student surveyed in a school said they will vote for nuncio for class president. Predict how many of the 340 students in the school would vote for nuncio?

3/4 is .75. translate that to percentages, and you get 75%. This means that it is likely that 75% of the 340 students in total will vote for Nuncio.
write it out:
.75*340
solve:
255

about 255 students are likely to vote for Nuncio