The diffrence of twice a number and 9 is -21

- 6

Step-by-step explanation:

Step 1:

2x - 9 = - 21       Equation

Step 2:

2x = - 12       Add 9 on both sides

Step 3:

- 12 ÷ 2     Divide

x = - 6

Hope This Helps :)

x = -6

Step-by-step explanation:

Let x = unknown number

2x -9 = -21

Add 9 to each side

2x -9+9 = -21+9

2x = -12

Divide by 2

2x/2= -12/2

x = -6

answer: a.   one is a factor of every whole number since every number is divisible by itself.