Android Layout code: main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
 
    <TextView
        android:id="@+id/label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10px"
        android:text="Enter amount:"/>

     <EditText
        android:id="@+id/initialAmount"
        android:layout_width="100px"
        android:layout_height="wrap_content"
        android:background="@android:drawable/editbox_background"
        android:layout_below="@id/label" />

    <TextView
        android:id="@+id/service"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15px"
        android:layout_below="@id/initialAmount"
        android:text="Select service:"/>
  
    <Button
        android:id="@+id/poorService"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/service"
        android:layout_marginTop="5px"
        android:layout_marginLeft="10dip"
        android:text="Poor" />
 
    <Button
        android:id="@+id/averageService"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/poorService"
        android:layout_alignTop="@id/poorService"
        android:text="Average" />
        
    <Button
        android:id="@+id/excellentService"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/averageService"
        android:layout_alignTop="@id/averageService"
        android:text="Excellent" />

    <TextView
        android:id="@+id/tipText"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15px"
        android:layout_below="@id/poorService"
        android:text="Tip:"/>

    <EditText
        android:id="@+id/tipAmount"
        android:layout_width="100px"
        android:layout_height="wrap_content"
        android:layout_marginTop="5px"
        android:background="@android:drawable/editbox_background"
        android:layout_below="@id/tipText"/>
        
    <TextView
        android:id="@+id/totalText"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15px"
        android:layout_below="@id/tipAmount"
        android:text="Total Amount:"/>

    <EditText
        android:id="@+id/totalAmount"
        android:layout_width="100px"
        android:layout_height="wrap_content"
        android:layout_marginTop="5px"
        android:background="@android:drawable/editbox_background"
        android:layout_below="@id/totalText"/>
        
</RelativeLayout>