The combination for a lock uses three of the digits 1, 2, 3, and 4. How many three-digit combinations can the lock have? Explain your answer.

24

Step-by-step explanation:

First you start by writing down all the combinations that start with each number. Then you just write the left over numbers and you'll end up with 24 because the is six of each starting number. Ex: 123, 132, 134, 143, 124, 142...

Hello,

x + x + 1 + x + 2 = 90

3x + 3 = 90

3x = 90 - 3 = 87

x = 87 / 3 = 29

29 ; 30 ; 31

The correct answer is C.

Bye :)