data/mathtoweb/285.mml
<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>|</mo><mi>A</mi><mo>|</mo><mo>=</mo><mrow><mo rspace="0.3em" lspace="0em" stretchy="true" fence="true" form="prefix">|</mo><mtable class="m-vmatrix"><mtr><mtd><mi>a</mi></mtd><mtd><mi>b</mi></mtd></mtr><mtr><mtd><mi>c</mi></mtd><mtd><mi>d</mi></mtd></mtr></mtable><mo rspace="0em" lspace="0.3em" stretchy="true" fence="true" form="postfix">|</mo></mrow><mo>=</mo><mi>a</mi><mi>d</mi><mo>-</mo><mi>b</mi><mi>c</mi></mrow></math>