After Anna spends $\dfrac{1}{3}$~of her money and loses $\dfrac{1}{2}$~of the remainder, she then has~$\textbackslash$10$ left. She started with． 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Finding the Base
After Anna spends $\dfrac{1}{3}$~of her money, she has $\dfrac{2}{3}$~left. If she loses $\dfrac{1}{2}$~of this, she has $\dfrac{1}{3}$~left. Since$\dfrac{1}{3}=$$\textbackslash$10$,~$\dfrac{3}{3}=3\times$$\textbackslash$10=$$\textbackslash$30$. 