Easy way to fill percent of layout on Android

You can use weightSum and layout_weight to fill percent of layout:

<LinearLayout
    android:layout_width="fill_parent" android:layout_height="fill_parent"
    android:orientation="horizontal" android:weightSum="100"
    android:gravity="center" >
    <ImageView
        android:layout_width="0dp" android:layout_height="wrap_content"
        android:layout_weight="60">
    </LinearLayout>
</LinearLayout>