<?xml-stylesheet type="text/xsl" href="pmathml.xsl"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<math>
  <mrow>
    <mi>Sp</mi>
    <mo>=</mo>
    <mrow>
      <mo>SUM</mo>
      <mfenced>
        <mrow>
          <mo>k</mo>
          <mo>&times;</mo>
          <mo>Sc</mo>
          <mfenced>
            <mrow>
              <mi>ta</mi>
              <mo>-</mo>
              <mi>to</mi>
            </mrow>
          </mfenced>
        </mrow>
      </mfenced>
    </mrow>
  </mrow>
</math>
