Solving Equations

In the past two grades, you have used tiles to model equations. This is a very good way to model how to solve an equation.

However, sometimes the numbers are too big and there aren't enough tiles. For example, x + 142 = 150.

But in order to solve this equation we can use the same steps we did when we modeled it.

Remember addition and subtraction are opposite operations. Multiplication and division are opposite operations.

Example 1 - Isolate the variable on the left by subtracting 142 from each side. This is the same as adding zero tiles.

x + 142 = 150

x + (142 - 142) = 150 - 142

Now you have

x + 0 = 8 OR

x = 8.

Always rewrite your equation on a new line each time you make a change to it.

Verify your solution by substituting your answer into the original equation.

x + 142 = 150

8 + 142 = 150

150 = 150

Example 2: Solve 5x = 20

Divide both sides of the equation by 5 in order to isolate the variable.

Check:

5x = 20

5(4) = 20

20 = 20