<div style="float: left; width: 100px; height: 50px;"></div>
<div style="float: left; clear: both; width: 50px; height: 50px;">
    <div style="width: 50px; height: 50px; background-color: green; margin-left: 50px"></div>
</div>
<div style="width: 150px;">
    <table cellpadding="0" style="width: 100px; height: 100px; border-collapse: collapse;"><tr><td style="vertical-align: top;">
        <div style="background-color: red; width: 50px; height: 50px;"></div>
    </td></tr></table>
</div>