Whenever you solve a one step equation you are finding the value of the variable. The key to solving one step equations with addition and subtraction is, whatever operation you perform on one side of the equation, you must also perform on the other side of the equation. In order to isolate your variable you will perform an “Inverse Operation” which means if you have an addition operation, the “inverse operation” is subtraction.Let’s look at some examples of one step equations.

### Example 1. One step equation with subtraction

X – 5 = 7

Step 1 In order to isolate the variable ( X ) add 5 to both sides

X – 5 + 5 = 7 + 5

Step 2. x = 12

### Example 2.

x -2 = (-10 )

Step 1 In order to isolate the variable add 2 to both sides

x -2 + 2 = (-10 ) + 2

Step 2 x = -8

### Example 3 This one step equation involves addition

x+4 = 10

-4 -4

x= 6

### Example 4

x-5.5 = 10

+5.5 = +5.5

x = 15.5

### Example 5

14 = y-3

+3 = +3

17 = y

**Transcript One Step Equations Addition and Subtraction**

One step equations with addition and subtraction. Let’s look at our problem. X minus five equals seven. What value minus five equals seven? I will add five to both sides, so X equals twelve. Now let’s take the same problem and slow it down. Let’s look at it slowly now. Because this is subtraction in order to undo that I will add five to both sides, because in an equation you have to do the same operation to both sides. If I add five to the left I must add five to the right. Now let’s simplify. Negative five plus five adds to zero. So all I’m left with on the left side is the value X on the right side I do the straight operation, seven plus five and that is equal to twelve. You will often see this with different sign numbers. I’m going to change it to X minus two is equal to negative ten. For this problem to undo and get the X by itself I will add two to the left and two to the right. The negative two and positive two still cancel and I’m left with X but on the right side I’m left with sign numbers. So negative ten plus two and when you have different sign you subtract and you have eight. Take the sign of the larger number which is eight. So X is equal to negative eight. In all equations you can go back, plug in your answer and check it. Twelve minus five does equal to seven, so that one checks, the second one negative eight minus two does add to negative ten.