Answer:
450 students ride a bus to school.
Explanation:
If 3 out of 4 middle school students attend class by bus, it could be stated that 75% of the students use this means of transport to get to class (3/4 = 0.75).
Therefore, if this school has a total of 600 students, and 75% of them use the bus, it could be stated that 450 students attend school using this means of transport (600 x 75/100 = 450).