new task "Durchschnitt" added

src/main/java/src/TasksFrame.java

@@ -87,6 +87,8 @@ public class TasksFrame extends JFrame {
 
         setupPI(100000);
 
+        setupDurchschnitt();
+
         setupEulerschePhiFunk();
 
         setupQuersumme();
@@ -106,6 +108,66 @@ public class TasksFrame extends JFrame {
 
     }
 
+    private void setupDurchschnitt() {
+
+        JPanel jPanel = setupPanel("Durchschnitt");
+
+        JButton button = new JButton("calculate");
+        button.setVisible(true);
+        button.setBounds(10, 65, 100, 30);
+        button.setBackground(Color.BLUE);
+
+        JTextField a = new JTextField();
+        a.setBounds(10, 40, 30, 20);
+        a.setVisible(true);
+        a.setFont(new java.awt.Font("Arial", Font.BOLD, 12));
+
+        JTextField b = new JTextField();
+        b.setBounds(50, 40, 30, 20);
+        b.setVisible(true);
+        b.setFont(new java.awt.Font("Arial", Font.BOLD, 12));
+
+        JTextField c = new JTextField();
+        c.setBounds(90, 40, 30, 20);
+        c.setVisible(true);
+        c.setFont(new java.awt.Font("Arial", Font.BOLD, 12));
+
+        JLabel jLabel = new JLabel();
+        jLabel.setVisible(true);
+        jLabel.setBounds(10,90,60,30);
+
+        jPanel.add(button);
+        jPanel.add(a);
+        jPanel.add(b);
+        jPanel.add(c);
+        jPanel.add(jLabel);
+
+        button.addActionListener(new ActionListener() {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+                String texta = a.getText();
+                String textb = b.getText();
+                String textc = c.getText();
+                Double val_a = Double.valueOf(texta);
+                Double val_b = Double.valueOf(textb);
+                Double val_c = Double.valueOf(textc);
+                double res = average(val_a, val_b, val_c);
+                jLabel.setText(String.valueOf(res));
+            }
+        });
+    }
+
+    public double average(double a, double b, double c) {
+
+        double sum = a + b + c;
+        double average = sum / 3;
+        double roundOff = Math.round(average * 100.0) / 100.0;
+        return roundOff;
+
+    }
+
+
+
     private void setupExponent() {
 
         JPanel jPanel = setupPanel("Potenzrechner");