Answer:
680
Step-by-step explanation:
Use the binomial coefficient where you choose
numbers out of
possible numbers and find the total amount of combinations since order does not matter:

Thus, you can make 680 three-non-repeating-number codes
Answer:
-2/5 -4/3 p and -4/3p+ (-2/5)
Answer: C
Step-by-step explanation: since he has 4 dice, there are 24 chances. But he needs 2 fives. That means 2/24 = 1/13. 1/13= C