Consider that the markup percentage, markup price, and retail price are related as,
[tex]\text{ Markup percent}=\frac{\text{ Retail Price}-\text{ Markup Price}}{\text{ Marked Price}}\cdot100[/tex]According to the given problem,
[tex]\begin{gathered} \text{ Markup Price}=128 \\ \text{Retail Price}=143 \end{gathered}[/tex]Substitute the values,
[tex]\begin{gathered} \text{ Markup percent}=\frac{143-128}{128}\cdot100 \\ \text{ Markup percent}=\frac{15}{128}\cdot100 \\ \text{ Markup percent}=11.71875 \end{gathered}[/tex]Thus, the markup percentage value is 11.71875%.