And so we could just say, well, w of this time, so I used uppercase w as my function for how much water is in the pipe, so capital w of lowercase w is going to be equal to 50. And so you would just solve for the w. And they say write, but do not solve, an equation. Well, just to make this a little bit clearer, if uppercase w of lowercase w is going to be 30 plus the integral from 0 to w, and actually now since I don't have t as one of my bounds, I could just say r of t minus d of t dt, so let me just do that. r of t minus d of t dt, so this is the amount of total water in the pipe at time w. Well, this is going to be equal to 50. So we have just written an equation involving one or more integrals that gives the time w when the pipe will begin to overflow. So if you could solve for w, that's the time that the pipe begins to overflow. And we are assuming that it doesn't just right get to 50 and then somehow come back down, that it will cross 50 at this time right here.