Gradeaverage App Will Not Start In Emulator

Im trying to make this app that calculates your grade average (based on the Swedish grade system) and I have made the graphical layout and written the java code in eclipse that I think is right, but when I try to launch it in the emulator it won�t work. I just get the following messege. "The application Gradeaverage (process com.dlol.gradeaverage) has stopped unexpectedly. try again.

It is supposed to be three edittexts where you put the amount of points you have with a cerrtain grade (we have three grades) and then it should multiply the points with the 10, 15 or 20 depending on what grade it is and then divide by the total amount of points. I dont know if that makes sense, but the maxmimum grade is supposed to be 20 (all mvgs). I made a similar app in C# and it works, but Im guessing things are done alittle diferent when it comes to android and java.

Here is the Java code:

Code:

package com.dlol.gradeaverage;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

[code]....