A math riddle?

Question

A school has 18 classes with 35 students in each class. In order to reduce the class size to 30, how many new classes must be formed?...explain. 10 points for best answer :-)

Answer 1

18 * 35 = 30 * X
X = 18 * 35/30 = 21 classes

Answer 2

18 classes times 35 students per class = a total of 630 students divide this by the desireed class size, 30 = 21 classes; therefore, 3 new classes must be formed to reduce class size from 35 to 30.

Answer 3

to reduce the classes to 30 there would need to be 3 more classes, as there are 5 over the amount wanted if you take 5 out of each class, you would be left with 90 spare students so simply sivide by 30 and you get 3 :D

Answer 4

3. You have 18 classes at the start with 35 students each.
18x35=630
630 divided by 30=21
21-18=3 classes that are new.

Answer 5

there are 5 extra student in each class and 18 classes to start so 5 X18 = 90 divide 30 = 3 so 3 new classes

Answer 6

18 classes * 35 students/class = 630 students

630 students = 30 students/class * X classes

X = 21 total classes

21 total classes - 18 old classes = 3 new classes

Answer 7

3 more classes, what I did to figure out was
1. get number of students by multiply 35*18
2. then divided that by 30
3. got answer

Answer 8

3 new classes because you take 5 students from each class, 6 groups of 5 students to a new class, 18 divided by 6 is 3, therefore 3 new classes would be formee. TA-DAH!!

Answer 9

35X18=630/30=21 in short 30-18=12 classes

Answer 10

18 *35 = 30 x
x = 18*35/30
x=3*7
x=21

21-18 = 3

3 new classes.

Not a "riddle type" answer but a mathematical type answer.