The quantity of ribbon Stacia used to make the costume is 16 feet
1 yard = 3 feet
6 yards = 18 feet
Quantity of ribbon Stacia used to make the costume = Total ribbon Stacia bought - Ribbon left over
= 18 feet - 2 feet
= 16 feet
Learn more about conversion of yards to feet:
https://brainly.com/question/770921