Question 8359
<pre>>>Please help me solve this equation: m + 18 = -9<<<b> 
                             m + 18 = -9
An equation is like a balance scale.  If you perform a mathematical operation
to one side of the equation, then you must perform the same mathematical
operation to the other side. The left side is
                             m + 18
We wish there were only the letter
                             m
on the left side and nothing else.  We wish the
                               + 18
weren't there.  So we need to get rid of the

                               + 18.
The only thing that we can use to get rid of the 
                               + 18
is
                                    - 18

so we insert

                                    - 18
after the                      + 18
and that makes the left side become
                             m + 18 - 18
However since we put - 18 at the end of the left side, we have no choice but to
also put 
                                        - 18

 at the end of the right side too!  That will make the right side
becoms
                                     -9 - 18
So here are the steps so far:
                            m + 18 = -9
                       m + 18 - 18 = -9 - 18
Now the + 18 - 18 on the left is just 0, so we can just erase
the + 18 - 18 on the left and get
                                 m = -9 - 18
Now the right side is -9 - 18 and that is -27, so the last step is
                                 m = -27
So altogether here are the steps as you should show them on your paper:
                            m + 18 = -9
                       m + 18 - 18 = -9 - 18
                                 m = -27     
That is the solution.  Now we check it:
                            m + 18 = -9
Replace m by -27
                          -27 + 18 = -9
                                -9 = -9
Since both sides of the equation are the same we know the answer is
correct.
Edwin