How can you check by calculation whether the combination of an articulated motor vehicle (semitrailer load = vertical load) exceeds the permissible total mass of the combination of vehicles?

You answered correctly. When checking if your articulated vehicle combination exceeds the permissible total mass, you need to consider the way the vertical load of the semitrailer affects the overall weight calculation. The permissible total mass of the truck tractor and the permissible total mass of the semitrailer must be added together, but you must subtract the vertical load (the portion of the semitrailer’s weight that rests on the truck tractor’s coupling). This is because that vertical load is already included in both the truck tractor’s and the semitrailer’s permissible mass figures. Subtracting it avoids double-counting. Remember, using the formula: permissible total mass of the truck tractor plus permissible total mass of the semitrailer minus vertical load will give you the correct way to check the legal weight limit for the combination. This ensures you do not exceed what is allowed by law.