It pays to be smart

Hey guys. This is my first story. Be nice and give me as much feedback as you want.

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“I’m just going to take a shower,” my girlfriend, Hannah called out.
“I’ll come too,” I called back.
“No, I need to wash my hair, so I’ll be a while.”
“Okay, I’ll put a movie on or something.” I went into the lounge room to choose a movie. As I was deciding, Hannah’s sister Nikki came wandering in.
“Hey Jack, how you doing?”
“Hey Nikki, I’m doing alright. How are you?”
“I’m fine. Would you be able to help me out with something?”
“Sure, what’s the problem?”
“Thanks! Come with me, I’ll show you.” With that, Nikki walked out of the lounge room. I followed her into her room where she sat down at her desk and pointed at a notebook. “I’m trying to figure out why my equations aren’t working. Do you have any ideas?”
Since I was studying high school teaching, majoring in maths, I could tell exactly what was wrong with her calculations. As I was explaining how to fix what she had done wrong, Hannah walked in and saw us working on the equations.

“What you guys doing?” she asked.
“Jack is giving me some help with my maths homework!” Nikki said brightly.
“Is he now?