其它
A meal was priced at $\textbackslash$80$. The shop offered Jane the meal at a $40\textbackslash\%$ discount. After service charges of $10\textbackslash\%$, how much did Jane pay for her meal? 
Overseas Competition->Knowledge Point->Counting Modules->Inclusion-Exclusion Principle
Price after discount $=\textbackslash$80\times(100\textbackslash\%-40\textbackslash\%)=\textbackslash$48$  Price after service charges $=\textbackslash$48\times110\textbackslash\%=\textbackslash$52.80$ 