<svg xmlns="http://www.w3.org/2000/svg" xmlns:html="http://www.w3.org/1999/xhtml">

<html:style>
  #mathy { display: table}
</html:style>

<foreignObject width="500" height="500" y="50">
  <div xmlns="http://www.w3.org/1999/xhtml">
    <p>Foo</p>
    <div>
      <math xmlns="http://www.w3.org/1998/Math/MathML" id="mathy" display="block">
        <mrow>
          <mi>x</mi>
        </mrow>
      </math>
    </div>
  </div>
</foreignObject>

</svg>