Boss gave his kid less work while giving us more

So we got our assigned sections to clean this upcoming school year and me and my co worker are livid he gave us three sections to clean throughout the building while only giving his kid one we immediately called him out on it asking why is he getting less work than us and his only excuse was he comes in a little early than us to help with cafeteria. I called out his favoritism since it’s his kid and he got super mad at us saying we should just quit and other schools wouldn’t treat us as good as this one. So now everyone is pissed at each other and he wants to have a group meeting soon honestly don’t know if I can even work with him anymore if his kid keeps getting an easy pass.