I've made a RC object in which there's a group of cars distributed on Markers. I've connected all the car models to a randomize node and I've connected both that randomize node and a null object to a second randomize node. I've exported the presense parameters for both objects and attached a numeric node to both. This allows me to manually control the presence of either a car or an empty parking space.
What I'm looking for is the expression (or a different way?) to have 1 percentage input control both percentages. I think there must be something like Value B = 100-Value A, but I really don't understand how I should put it in the node.