So some c in this interval. So some c, some c in between it, where the instantaneous rate of change at, at that x value is the same as the average rate of change. So there exists some c in this open interval where the average rate of change is equal to the instantaneous rate of change at that point. That's all it's saying. And as we saw in this diagram right over here, this could be our c, or this could be our c as well. So nothing, nothing really, it looks, you know, you would say f is continuous over a, b, differentiable over, over, f is continuous over the closed interval, differentiable over the open interval, and you see all of this notation, you're like, what is that telling us? All it's saying is, at some point in the interval, the instantaneous rate of change is going to be the same as the average rate of change over the whole interval.