From the information given, you know that $13 represents 20% of the original price and you can use a rule of three to find the value that represents 100%, which would be the original pice of her purchase:
$13 → 20%
x ← 100%
x=(13*100)/20
x=1300/20
x=65
According to this, the answer is that the original price of her purchase was $65.
