How to write a PHP code on simple math expression?
<p>I am a newbie of PHP coding, and want to do a simple math example, <strong>d=(a+b)/c</strong>.</p>

<p>The values of <strong>a</strong> and <strong>b</strong> will be submitted by the user from a webpage containing PHP form.
The value of <strong>c</strong> is predefined in the PHP page.</p>

<p>When the user click "submit" in this webpage. 
I expect to get the result of <strong>d</strong> in the bottom of the same webpage.</p>

<p>Any example code will be greatly appreciated.</p>
