Neither of the two photocopiers in our office works very well.  Photocopier $$\text{A}$$ produces $$1$$ \textquotesingle bad\textquotesingle{} copy for every $$4$$ \textquotesingle good\textquotesingle{} ones.  Photocopier $$\text{B}$$ produces $$1$$ \textquotesingle bad\textquotesingle{} copy for every $$5$$ \textquotesingle good\textquotesingle{} ones.  We need to produce $$600$$ \textquotesingle good\textquotesingle{} copies of a poster.  $$\frac{3}{5}$$ of the \textquotesingle good\textquotesingle{} copies will be produced by Photocopier $$\text{A}$$.  $$\frac{2}{5}$$ of the \textquotesingle good\textquotesingle{} copies will be produced by Photocopier $$\text{B}$$.  How many copies in total (including the \textquotesingle bad\textquotesingle{} ones) will be needed? 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Knowing the Base