Explanation
Given the donors as
[tex]\begin{gathered} Gold=4 \\ silver=7 \\ Bronze=9 \end{gathered}[/tex]The total number of donors are
[tex]9+7+4=20[/tex]Therefore, the percent of donors at the bronze or silver level is
[tex]\frac{sum\text{ }of\text{ }bronze\text{ }and\text{ }silver\text{ donors}}{number\text{ of donors}}=\frac{9+7}{20}\times100=16\times5=80\text{\%}[/tex]Answer: