Miley had some keychains at first. She gave $$\frac{6}{7}$$ of them to her friends. Her mother then gave her another $$8$$ keychains. She had $$15$$ keychains in the end. How many keychains did Miley give to her friends in total? 
Overseas In-curriculum->Knowledge Point->Operations of Numbers ->Word Problems Involving Fractions and Percentages->Finding a Whole Given a Part and the Percentage Overseas Competition->Knowledge Point->Counting Modules
$\frac{1}{7}$ of her keychains $=15-8=7$  $\textasciitilde$  Given to friends  $=\frac{6}{7}$ of her keychains  $=7\times6$  $=42$ 