Luann has a piece of ribbon that is 1 yard long. She cuts 33 inches off to tie a gift box. How many inches of ribbon are not used?

First, we convert the given initial length of the ribbon by the conversion factors,

1 yd = 3 ft

1 ft = 12 inches

Converting,

(1 yd) (3 ft / 1 yd) (12 in/1 ft) = 36 in

Since Luann used 33 inches, the length of the unused ribbon is 3 inches.