well, from those 560, 200 are from her salary, and the rest is commissions from sales, so.... 360 is the 5.5% she's got, now, if we take "x" to be the 100% for the sales, then
[tex]\bf \begin{array}{ccllll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
360&5.5\\
x&100
\end{array}\implies \cfrac{300}{x}=\cfrac{5.5}{100}[/tex]
solve for "x".