Delete the containing RelativeLayout (since it is the only descendant of your root LinearLayout that you don't need) or change it to LinearLayout.
Then, for both the Pen layout and the bottle layout, add the android: layout_weight attribute and set both of them to 1.
Make sure both layouts have the height set in MATCH_PARENT
Now your two layouts should share the space equally between them, thereby making them the same height.
To divide the space evenly between the children of the Pen and Bottle layouts, I suggest you set the height of each child element to WRAP_CONTENT, and the layout_weight of each of them to 1.
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