Fractions
A MathML tag creating a fraction will contain 2 elements within the tags. Rows can be used here to add more than a single element to a fractions numerator or denominator.
The tag used to denote a fraction is the <mfrac></mfrac> tag. So a typical fraction is written as:
<math><mfrac><mn>2</mn><mn>3</mn></mfrac></math> resulting in
Using rows in the mathML instead allows for more elements to be added. For example:
<math><mfrac><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>3</mn><mo>)</mo></mrow><mn>5</mn></mfrac></math>
resulting in
