Small applets for simplifying expressions

Simplify algebraic Expression

I created four different small apps for simplifying expressions. Every applet is a game, in which you collect points. 

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<iframe fullscreen="" height="160px" scrolling="no" src="https://www.geogebra.org/material/iframe/id/tzx7uaem/width/300/height/160/border/000000/rc/false/ai/false/sdz/false/smb/false/stb/false/stbh/false/ld/false/sri/false" style="border: 0px;" width="300px"> </iframe>