A class of 40 students elected a class president. There were 12 votes for Candidate A, and 18 votes for Candidate B. The remaining students in the class did not vote. Which expression gives the percent of voters who voted for Candidate A?

The answer is 40%
There are 30 people who voted, and your looking for the % of people who voted for Candidate A, so in order to find the % you divide 12 / 30, then multiply
0.4 * 100 = 40%