Glenda poured salt into three salt shakers from a box that contained 26 ounces of salt. She poured 2 ounces of salt into one shaker, 3 ounces of salt into the second shaker, and 4 ounces into the third shaker. She did not pour salt into any other shakers. Which expression best represents the amount of salt left in the box after Glenda poured salt into the three shakers?