1. Solving Linear Equations
with Addition
and Subtraction

2. to one side of an equation,
When you do something
to one side of an equation,

3. you have to do exactly
the same thing
to the other side.

4. To solve an equation means
to find every number that makes the equation true.

5. In the equation,
x is the number
you add to 7
to get 15.

6. What is the number?
8, of course.

7. What is the number?
8, of course.

8. So we would write the solution,
What is the number?
8, of course.
So we would write the solution, .

9. the solution is obvious.
In some equations,
the solution is obvious.

10. the solution is not so obvious.
But in other equations,
the solution is not so obvious.

11. a way to solve equations.
Many times we need
a way to solve equations.

12. To understand one way,
we can work backwards.
Start with a solution,

13. And create another equation by changing both sides.

14. To solve that equation, you can just undo what you did.

15. To solve that equation, you can just undo what you did.

16. To solve that equation, you can just undo what you did.

17. To solve that equation, you can just undo what you did.

18. Now you see how easy solving these types of equations can be.

19. If you had started with the solution,
what would you have done to get this equation?
Hint

20. And if you subtracted 12 from both sides,
what would you do to get the original solution?

21. Right!
You would need to
add 12 to both sides.

22. As you solve these equations,
think about what you need to do to get the variable by itself on one side of the equation.
As you solve these equations,

23. Think about what you need to do isolate the variable.

24. 1. 2. 3. 4.