Step-by-step explanation:
Total numbers of pizza toppings = 12
Number of three topping pizzas can be ordered are:
[tex]P^{n}_{k}=\frac{n!}{(n-k)!}[/tex]
where = n = number of elements
k = number of elements choosen
n= 12 , k = 3
[tex]\frac{12!}{(12-3)!} =\frac{12\times 11\times 10\times 9!}{9!}= 1,320[/tex]
We calculated the number of permutations. We made this choice because in permutation order of element matters but in combination its not.
