You are trying to hack into your friend’s phone. The password is four digits long and each number can be a digit from 0 to 9. If the numbers can repeat, how many possible combinations are there?

10,000

Step-by-step explanation:

10 x 10 x 10 x 10

81 times its common sense but you dont have nun.

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10