<p>The answer to this problem is C, why isn't it A? <a href="http://i50.tinypic.com/2q3cepy.jpg%5B/url%5D">http://i50.tinypic.com/2q3cepy.jpg</a></p>
<p>because the addition and subtraction of exponents only works with multiplication and division, respectively.</p>
<p>Exponents tell you how many times you multiply the base by itself…so you can only change (add/subtract) exponents when you multiply/divide, not add/subtract</p>
<p>Plug in numbers to see it</p>