If you are trying to find what \(\displaystyle n\) is equal to in \(\displaystyle n\,=\,29.26\,-\,2k\)
When \(\displaystyle k\,=\,8.44\), then you substitute \(\displaystyle k\) in your equation:
\(\displaystyle \L \;n\,=\,29.26\,-\,2(8.44)\)
Then follow the Order of Operations, first multiplication: \(\displaystyle \L \;n\,=\,29.26\,-\,16.88\)
Finally subtraction: \(\displaystyle \L \;n\,=\,12.38\)