Adding and Subtracting Matrices

$$\text{Intern Day}$$

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Today (July 27) is National Intern Day! To celebrate, I'm going to let Expii Intern Mark take this one.

$\color{purple}{\text{Uhhhhhh hey everyone, this is Mark. So I guess I have to write a problem for}}$ $\color{purple}{\text{all of you. I don't really know Latex yet though. Honestly, I just started five}}$ $\color{purple}{\text{minutes ago. This is all a little overwhelming. Oh jeez. Okay, matrices.}}$ $\color{purple}{\text{Aw, that didn't work at all. Alex is screaming at me now. I really don't like}}$ $\color{purple}{\text{this job.}}$

Sorry everyone, this is Alex again. Mark has been fired. That was a disaster. Please just solve the problem below and forget any of this happened.