Mathematical Function

Can someone tell me how to calculate mathematical function. For example I need to calculate:

When you press button Calculate to show in TextBox3 result from TextBox1 divided by TextBox2.

Also me need another mathematical function but I don't now how to make that in program?

Can you help me with this function?

Please do the tutorials... You need to learn how to use AI before doing what you're trying to do!  The tutorials are located here:http://appinventor.mit.edu/explore/ai2/tutorials

...also read http://www.appinventor.org/Chapter16     in the AI2 free online eBook   http://www.appinventor.org/book2 ... the links are at the bottom of the Web page.

set TextBox3.text to   TextBox1.Text / TextBox2.Text   is what you say you want to do.

Now, do some reading and try some blocks.   If you run into difficulty, post a screen capture image of what you tried (jpg or png images please) and someone will provide specific advice.