Kristin received a CD player for her birthday. She bought 3 CDs and received 5 others as gifts. What fraction of her total CDs did she buy and what fraction dis she receive as gifts?
According to the question,
Total number of CDs that Kristin had on her birthday = 3 + 5
= 8
Now,
Among those 8 CD,
3 CDs were bought by her
And,
5 CDs were gifted to her on her birthday.
Hence,
She bought and received CDs as gifts in fraction as 
respectively.
18