This is a neat concept. Intense music going on while solving math problems quickly to load your gun is a vibe. Shooting itself worked great. I think an issue I encountered was having to click into the box to solve the math problems. With how quickly the enemies are spawning I should just be able to type in a number and hit enter. I was also encountering an issue with swapping weapons. I would hit shift and it acted like was swapping but then swap right back.
Think you're on the right track to making a fun math learning game! Good job!