This is how I showed Austin. Personally I would have solved it differently, but it’s math that is beyond him.
(Sorry I cut off part of my image)
I think an easier way to solve, using a bar model is to say if 2/5 is 3600, each 1/5 is 1800 meters. Then the total cycled plus ran is 1800×5 or 9000 meters. So if 3/4 if the race is 9000, each 1/4 is 3000. So 3000×4 is 12000 meters total.
But I don’t know if that is an acceptable way to teach him.
What are your thoughts?