The combined gas law is a gas law which combines Charles's law, Boyle's law, and Gay-Lussac's law. The combined gas law integrates Charles’s law, Boyle’s law, and Gay-Lussac’s law. Each of these gas laws relates one thermodynamic variable to another mathematically, but holds everything else constant. Each of the combined laws shows that two variables are in proportion to one another, while the combined gas law itself demonstrates that these three laws are actually inter-dependent.