A school has 18 classes with 35 students in each class. In order to reduce class size to 30, how many new classes must be formed?
3
Explanation
The number of students in the school \(18 \times 35=630\). If there are to be 30 students in a class, the number of classes needed is 630 / 30 = 21.
Therefore, the number of new classes needed is 21 - 18 = 3.