And the mean value theorem tells us that there exists, so if we know these two things about the function, then there exists, there exists some, some x value in between a and b. So in the open interval between a and b, there exists some c, there exists some c, and we could say it's a member of the open interval between a and b, between a and b. Or we could say some c such that a is less than, such that a is less than c, which is less than b. 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.