Solving for X

Date: 8/14/96 at 1:54:57
From: Anonymous
Subject: Solving for x

Solve  1
       - x -4 = -2.
       7

Date: 8/14/96 at 3:25:42
From: Doctor Mike
Subject: Re: algebra

Hello,
  
First I'll start by re-writing this equation all on one line
computer e-mail style as  (x/7) - 4 = -2. This equation is
something that is given to be true about some unknown number x.
The left side of the equation is equal to the right side, right?
So we should be able to do exactly the same thing to both the
left side and to the right side, and still wind up with a true
equation.  

What I'm going to choose to do is to "add four" to both sides.  
Why would I do that?  Because then I get a really helpful equation  
(x/7) = 2. [I get (x/7) on the left because the +4 and -4 make 
zero; I get 2 on the right since 4-2=2]. 

Now the equation says that "x divided by 7" or "one seventh of x" 
is equal to 2. So x itself is seven times two which is 14, and the
answer is 14. See how it's done? 
  
By the way, another good way to look at that last step also 
amounts to doing the exact same thing to both sides of an
equation.  If you multiply each side of the equation (x/7) = 2 
by 7, then you get the final equation  x = 2*7 = 14. 
  
I hope this helps.  Write back if you have more questions.  

-Doctor Mike,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/