backround image not show in sub folder form

Question

dear all
i use following code in master page
<td class="masterstyle14"
style="background-image: url('images/left_top.jpg'); font-weight: 700; color: #0033CC;">
Quick Links</td>
but when in my webapplication i use this master page in subfolder form then background image not show
plz send me solution if any one know