It is given that the original cost is 450 and the selling price is 300.
The markdown is given by:
[tex]450-300=150\text{ pesos}[/tex]So the markdown in 150 pesos.
The markdown rate is calculated as follows:
[tex]\begin{gathered} \text{ Selling price=(1-Markdown rate)(Original price)} \\ 300=(1-x)(450) \\ \frac{300}{450}=1-x \\ x=1-\frac{300}{450} \\ x=\frac{150}{450} \\ x=\frac{1}{3} \\ x=0.3333 \end{gathered}[/tex]The markdown rate is 0.3333 or 33.33%.