Embellished Word Aesthetic: they replaced the I work a - marking. This shows both the word and the meaning. They made the - red to allow the viewer to connect it with the actual way math problems are written in books.
The meaning of the word "missing" is portrayed frm the absences of stem of the letter "i". By leaving the titles, it portrays that a part of the letter has been removed, reinforcing the meaning of "missing".