Error 1: Incorrect closing tag order

Example:
<president>Bill Gates
<extension>09-9990011</president></extension>

Tags are incorrectly nested.
</president> is closed before </extension>.
XML requires proper nesting.

Correction:

<president>
    Bill Gates
    <extension>09-9990011</extension>
</president>

Error 2: Same nesting problem for secretary

Example:

<secretary>Katharine Finch <extension>09-9990012</secretary></extension>

Incorrect closing order of tags.

Correction:

<secretary>
    Katharine Finch
    <extension>09-9990012</extension>
</secretary>