A combination lock has 6 different numbers. If each number can only be used ONCE, how many different combinations are possible?

151200 possible combinations

Step-by-step explanation:

There are 10 digits 0 - 9  ( 0,1,2,3,4,5,6,7,8,9)

There are 10 choices for the first digit

10

There are 9 choices for the second digit

9

There are 8 choices for the third digit

8

and so on  since we can only use each digit once

10 *9*8 *7 *6*5

151200 possible combinations

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x