I need you to develop some software for me. I would like this software to be developed for Windows using .NET. I need an application that allows users to select items from a list, connect via an API, and conduct basic mathematical calculations and then use an API to submit it back. The UI is very simple. The application should be written in C# and be done as a WPF application. Submitted work should include all source code and files, and the solution file for Visual Studio. I use VS 2015. All work must be well commented.