Bow, Cap, and Glasses: Math Problem

Characters: Rebecca(girl with the pigtails), Steve(the guy who solved that horrendous quadratic equation)

This is also another comic strip I made last spring.
This was one of my ideas for my intro comic to the series; I quickly rejected it though.
_{Okay, I verified the answer to that equation with Desmos and Wolfram Alpha. If it's still incorrect, then this would be very embarrassing...}

Regarding the last panel:
There was a thought bubble Rebecca had, that I deleted, hence the positioning of the speech bubbles.
I didn't have the time and energy to re-edit; I also managed to convince myself that the positions of the speech bubbles are good enough.

This is comic strip #4
Click here for other Bow, Cap, and Glasses comic strips