如何取到div class="a"下面<div style="display: block; "><span class="num">的值2500

<div class="a">
<div style="display: block; ">
<table>
<tbody><tr>

<div class="title">
<span class="num">2500</span>
</div>
</div>
</td>
</tr>
</tbody></table>
</div>


<div style="display: none; ">
<table>
<tbody><tr>

<div class="title">
<span class="num">2700</span>
</div>
</div>
</td>
</tr>
</tbody></table>
</div>


</div>