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Gilda has a bag of marbles. She gives $30 \textbackslash\%$ of them to her friend Pedro. Then Gilda gives $25 \textbackslash\%$ of what is left to another friend, Ebony. Finally, Gilda gives $10 \textbackslash\%$ of what is now left in the bag to her brother Jimmy. What percentage of her original bag of marbles does Gilda have left for herself? (adapted 2019 AMC 8, Question \#8) 
Overseas Competition->Knowledge Point->Calculation Modules->Percentage Calculation
After Gilda gives $30 \textbackslash\%$ of the marbles to Pedro, she has $70 \textbackslash\%$ of the marbles left. If she then gives $25 \textbackslash\%$ of what\textquotesingle s left to Ebony, she has $(0.75 * 0.70)=52.5 \textbackslash\%$ of what she had at the beginning. Finally, she gives $10 \textbackslash\%$ of what\textquotesingle s left to her brother, so she has $(0.9 * 0.525) =$ (A) $47.25\textbackslash\%$ of what she had in the beginning left. 