以PHP&；为单位计算每件物品的数量成本；MySQL

我正在制作一个名为“街头暴徒”的基于文本的角色扮演游戏，我正在编写黑市页面，这个页面现在已经完成，除了我想根据用户销售的数量计算每件商品的价格之外

例如，“Ryan以500000000美元的价格出售了5个信用卡”-现在我想要一个PHP算法告诉我，这些信用卡每件价值100000000美元。。。。我不认为我能更好地解释这一点，但任何帮助都将不胜感激。。。（我还附上了一张照片，试图更好地解释这一点……）

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您没有尝试我帮助您启动的任何东西（并且想要使用regex）：

写下你尝试过的东西。代码在哪里？这是一个帮助启动询问者的示例
<? 

$query=mysql_query("SELECT * FROM blackmarket_credits ORDER BY id");

$nums =mysql_num_rows($query);


if ($nums == "0"){

echo "<tr><td colspan='6' align='center'>The market is currently empty!</td></tr>";  }

while($i = mysql_fetch_object($query)){

$blah =mysql_query("SELECT * FROM users WHERE username='$i->username'");

$users =mysql_fetch_object($blah);

if ($i->expires > time()){

$timeleft = $i->expires - time();

if ($i->username == "$username"){$show = "<img width='16px' height='16px' src='/images/icons/cross.png' onclick=\"window.location.href='?type=points&remove=$i->id'\">"; }elseif ($i->owner != "$username"){ $show = "<img width='16px' height='16px' src='/images/icons/tick.png' onclick=\"window.location.href='?type=points&buy=$i->id&id=$i->id'\">";}

if ($col=="0"){ $td="151515"; $col="1"; }else{ $td="000000"; $col="0"; }

echo "<tr style='background-color: #$td'>
<td valign='baseline' height='40'><br><div style='display: inline-block;z-index: 10;position: relative; width: 30px;height: 30px;'>
    <img src='$users->avatar' width='30' height='30'>
    <div style='position: absolute; bottom: 0px; right: 0px;'><img src='/images/blip_offline.png' width='10'></div>
</div> &nbsp; </td>
<td align='left' height='40'><a href=profile.php?viewuser=$i->username>$i->username</a></td>

<td align='left' height='40'>".number_format($i->quantity)." Credits</td>

<td align='left' height='40'>&dollar;".number_format($i->cost)."<br><span style='color:#777'>&dollar;".number_format($THIS IS WHAT I'M ATTEMPTING TO GET)." per item</span></td>

<td align='left' height='40'><span id='timer1'></span><script type='text/javascript'>setTimer('timer1','$timeleft', { 0: function () { window.location = 'black_market.php' }});    </script></td>

<td align=center height='40'>$show</td></tr>"; }}  ?>

    function calcCostPerItem($totalPrice, $quantityItems) {

      return preg_replace("/\D(\d+).(\d+).(\d+).(\d+)/", "$1$2$3$4", $totalPrice) / $quantityItems;

     }

echo calcCostPerItem('$500.000.000.000', 5); //result 100000000000