You can divide by 120 if you use the approach I mentioned - dividing the power on each leg by 120. The power for a 240V device, like EV charging will be split between both legs. So in your example, the toaster is 10A on just one leg. The EV shows as 5A on each of the two legs - that’s 10A total. And as I pointed out earlier, you’ll want to look at power/amperage for each leg against the 200A (really 160A) limit.