A toy stores percent of markup is 30%. A model train costs the store $80. Find the markup.

if we take 80 to be the 100%, what is 30% off of that anyway?

[tex]\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 80&100\\ x&30 \end{array}\implies \cfrac{80}{x}=\cfrac{100}{30}\implies \cfrac{80\cdot 30}{100}=x[/tex]

so the markup amount is "x".