The variable S, I and R stand for Susceptible, Infectious and Recovered classes. So the dS/dt, dI/dt, and dR/dt stand for the rate of chance with time of these numbers. Hope that helps!

## The variable S, I and R stand

The variable S, I and R stand for Susceptible, Infectious and Recovered classes. So the dS/dt, dI/dt, and dR/dt stand for the rate of chance with time of these numbers. Hope that helps!