X - 3= -21
This is so confusing:(

Step-by-step explanation:

In order to solve this, we are trying to find the value of . Basically, is a placeholder for a number that is unknown. Some number minus 3 is equal to 21.

Our goal is to find . To do this we want to isolate on one side of the equation

Let's add 3 to both sides.

Hope this helped!

x = -18

Step-by-step explanation:

x - 3 = -21

add 3 to both sides

x - 3 + 3 = -21 + 3

x = -18

sidenote: you can add anything to both sides of an equation, and it'll still be true. for example, 2 = 2, if you add 1 to both sides you get 3=3 which is still true.