Magento Show Discount in Special Price.

Add this code in template > catalog > product > price.phtml

<?php if($_finalPrice < $_price): ?>    
<?php $_savePercent = 100 - round(($_finalPrice / $_price) * 100); $_saveAmount = number_format(($_price - $_finalPrice), 2); ?>        
<p class="yousave">           
    <span class="price-label label">You Save: </span>           
    <span class="price">
        <strong class="save-amount">$<?php echo $_saveAmount; ?></strong> (<?php echo $_savePercent; ?>%)
    </span>
</p>   
<?php endif; ?>