When I've charged at places other then home (for example right now the the Omni Richmond Hotel which has a Tesla HPWC) the dash-indicated mph charging rate shows two numbers. The Omni charger is indicating 24+15. Do we add the two to get the actual rate? And why the two numbers? At other places I've seen numbers such a 30 +3. I'm confused. To add to the confusion, at home I charge at a 39 mph rate, with no + indicated. So I'm puzzled about the Tesla Omni charger, which I think would charge at a much higher rate.