Devi is $$9$$ years old and Valli is $$13$$ years old now. What is the ratio of Devi\textquotesingle s age to Valli\textquotesingle s age in $$5$$ years\textquotesingle{} time? 
Overseas Competition->Knowledge Point->Calculation Modules->Ratios and Proportions->Ratio
$5$ years later,  Devi is $9+5=14$ years old and Valli is $13+5=18$ years old.  $D:V$ $=$ $14:18$ $\to$ $7:9$ 