Final answer:
Wendy had c - 8 hair clips.
Step-by-step explanation:
Let's represent the number of hair clips Wendy had as x.
We are given that Wendy had eight less hair clips than her sister. Since her sister had c clips, we can write a mathematical expression for Wendy's hair clips as x = c - 8.
Therefore, Wendy had c - 8 hair clips.