let's say the original price was "x", so that'd be the 100%, but he got a rebate of 5% off the regular price, and it ended up at 11566, so, 11566 is 100% - 5% or 95%.
now, if we know that 11566 is the 95% from the original price, what is "x"?
[tex]\bf \begin{array}{ccll}
a&b\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
x&100\\
11566&95
\end{array}\implies \cfrac{x}{11566}=\cfrac{100}{95}\implies x=\cfrac{11566\cdot 100}{95}[/tex]