Can someone me with numbers 5, 7, & 8?

earlier today i set you ten questions from this year’s international singapore maths competition. here are the questions and the answers. on the whole you did very well - smarter than a 10-year-old singaporean! (with the caveat that they didn’t have multiple choice answers to choose from, and they are only ten). the only questions where your most popular answer the wrong one were 6 and 8. (c in q6, and b in q8). for taking part - now look through your

at hatfield elementary school, there are 504 students in 7 classes. each class has the same number of students. what is a good estimate of the number of students in each class?