Let's begin by listing out the information given to us:
Percent markup (m) = ?, Cost (c) = $99.50, Selling price (p) = $124.38
The formula for percent markup is given by:
[tex]\begin{gathered} \text{\% }Markup=\frac{SellingPrice-Cost}{Cost}\cdot100\text{ \%} \\ m=\frac{p-c}{c}\cdot100\text{ \%}=\frac{124.38-99.50}{99.50}\cdot100\text{ \%} \\ m=25.005\text{\%}=\text{ }25\text{ \%} \\ m=25\text{ \%} \end{gathered}[/tex]The percent markup is 25%