And this equation is known as the ideal gas law. Now, recall that pressure is inversely proportional to volume which is exactly what this guy says. Pressure is inverse proportional to volume and directly proportional to N and T.
That's exactly what Charles Law in Evagondjo's Law tells us. Now, the only problem in this top portion is that we want to go from a proportionality sign to an equal sign. The way we adjust this guy, this top guy, so that we can equal them is by multiplying our right side or adjusting our right side by some constant R.
This is known as the ideal gas constant. So what problem remains?