i have two collections, paper and pens. Each one of this collections have elements inside, i show them in a treeview(collections), and the elements in a listview. For example, the collection pens is populated with 2 elements, blue and red pens, each one of this items have a field that is theamount.

I want to make a graphic that shows for example, how many blue and red pens i have.

thanks for your help!