Break your laptop and get a new one
When in doubt, decompose (break into smaller parts) the problem!
You need to display a GUI.
You need to accept input from two widgets and convert it integers.
You need to add a range of numbers.
You need to concatenate a string of what you're doing with the addition.
You need to display an answer in a widget and maybe redraw the window.
I've been having success copying the assignment into my source file and decomposing it as comments to frame out my program.
It was the Osborne 1 made by Adam Osborne in 1981.
Answer:
135 minutes or and 2 hrs and 15 minutes
