I am in the process of designing my first Android application and I am trying to get the hang of creating an XML layout. (I have a great deal of experience with Java)

Essentially what I wanna do:

![http://i.imgur.com/ZgbvYsX.png](https://i.stack.imgur.com/21ErH.png)

Where the outlines describes:

**Blue:** A basic View (where i can set a text)

**Red:** A ButtonView (Used so the user can synchronize data)

**Green:** A nested RelativeLayout (Where i am going to add a lot of other stuff)

More specifically what i wanna do:

![enter image description here](https://i.stack.imgur.com/oYLX6.png)

So my question is this: How can i set up the different layouts? I am having the must trouble with setting up the blue and red views because i want the red view to fill up around 25% of the screen width(and the blue to fill up the last 75%).

Thank you in advance.