$\frac{1}{7}$ of her keychains $=15-8=7$  $\textasciitilde$  Given to friends  $=\frac{6}{7}$ of her keychains  $=7\times6$  $=42$ 
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? 
Options:
a. $$42$$ 
b. $$48$$ 
c. $$49$$ 
d. $$90$$ 