Step-by-step explanation:
Total numbers of pizza toppings = 12
Number of three topping pizzas can be ordered are:

where = n = number of elements
k = number of elements choosen
n= 12 , k = 3

We calculated the number of permutations. We made this choice because in permutation order of element matters but in combination its not.
You are 22. If you add 22+5 you get 27. And if you divide 27 by 9 you get 3. So it is 22
1/8 is rational because irrational numbers can be written as decimals but not fractions
There are 3 boxes, each box has 93 tangerines.

There are 279 tangerines. They will be divided equally among 9 classrooms.

Each classroom will get 31 tangerines.