I could go look up the information, but so could you can you which will teach you more so I’ll give you information that will better understand the info you look up. Joanne is exactly right on RER. You can find this in any textbook and probably online, although you are pretty close with your figures.
A key thing to remember is that everyone is different. The goal is to be less reliant on carbs the higher intensity we go. This allows us to use a store everyone (including skinny marathon runners) has a lot of- fat. The longer we can keep from using glycogen the better! A good way to test this is if you (or your clients) can exercise while fasting and not have a drop in performance then they are good at burning fat. If they struggle a lot, then they are normally burning a lot of sugars when exercising.