Horribly laid out.
This game in a visual concept is very dull. White background, circular buttons, plain black text. There's nothing interesting about this game from glance... and it is important to have a visually expansive game if it's just a point'n'click.
Now, the math. VERY basic, but I fear you're trying too hard to make it look complicated. Instead of using key substations, try and write it out in page. The equations were simple, but deciphering all the jumble that is the keyboard substitutes was more time consuming.
Games like this also are best for taxing ones time in solving said problems. A timer and point allocation would go well, rewarding points for quicker answers.
The music was distracting and wasn't needed. Don't play a generic techno song that's heavy on beat, play something simple, allowing the user to concentrate more on the math.
Difficulty setting wouldn't go a miss either. I'd at least like to try something more difficult next time.
Good luck in the future.