Here is the item:
In the restroom, Tishena was brushing her hair,
freshened her lip-gloss, and
took deep breaths, trying to work up the courage
to walk to her first speech class.
Good choice! When you list actions, you must use parallel structure. Here, freshened and took are both simple past tense verbs, but was brushing is past progressive, wrecking the parallelism.
To fix the item, change was brushing to brushed.