Making use of an airport wait. What about this for an idea?

I've written a new version of this using this representation I learned of from Don Steward. Some people suggested algebra might put pupils off. I'm not sure this draws attention to patterns such as -d-(-d). Considering writing a 'multiple representations' version. Thoughts?

Click on this image to see a potential idea for drawing them together. I'm not sure.

I think Don's original tasks https://donsteward.blogspot.com/2011/03/addingsubtracting-directed-numbers.html?m=1 do this really nicely.