#### Answer

x-2

#### Work Step by Step

We can see in three pictures that Serena always wraps two boxes more than Tyler. In the first picture, Serena already has two boxes while Tyler is not even in the picture, meaning she has zero. In the second picture, Serena wrapped three boxes while Tyler has 1. In the third picture, Serena has 4, and Tyler has 2. Therefore, the expression should be x-2 when x=the number of wrapped boxes by Serena.