Answer: The total number of student in the school = 240.
Explanation:
Let x be the total number of students in the school.
Given: 35% of the students at Charles drew middle school are 6th graders.
i.e. Number of sixth graders = 35% of x = 0.35x [35% = 0.35]
Since there are 84 sixth graders in the school,
So

Divide both sides by 0.35, we get

Hence, the total number of student in the school = 240.