Yeah, it would help if you had a corresponding image with the colors that let you know what mathematical function you're trying to do. I'm constantly scrolling back and forth trying to remember, "what function is blue? what function is red?"

The rules should be obvious in-game rather than using just the HELP page.
I would also state clearly in text that you need to SWAP squares by clicking or click-dragging them.
I would include colored arrows with the math symbols inside.
For left to right I would have a fat arrow with a plus sign inside pointing to the right.
For right to left I would have a fat arrow with a minus sign inside pointing to the left.
Both arrows would be spaced on the line dividing the boxes from each other. One would be above the other arrow. With a crude ascii image below to give example.
(+)=>
<=(-)
If you want to make it simpler for the non-math inclined, you could also have a running total (updates changes as the boxes are swapped around) of the math results of the columns.

Realy cool game,makes people think!

Could be better, my first complaint is the lack of a mute button (and if it exists, it was at least hard enough to find for me to continue to bother).
A worked example would be helpful (or tutorial explaining the basics of the game) even after reading the instructions It was trial and error before I finally got how it works.
And finally, the green on white (for me at least) is doing my eyes in, others may not suffer from the colours like I do

Overall, it was fun to test out my brains basic maths for a short bit.

Nice math game. I felt the timer was a little unnecessary, as there is no real consequence for not completing the level in time. I can just reset, remembering everything on the try before (I'm not the fastest thinker). So it just became an annoyance. Besides that I really enjoyed it.