Well, that's just going to be equal to 1 1 2 times b prime of t sub zero times h of t sub zero plus b of t sub zero times h prime of t sub zero. Now, this might seem daunting, except they've given us a lot of this information. What is b prime of t sub zero? Well, they tell us the rate of change of b with respect to time, and it seems like it's just gonna stay at negative 13 meters per hour, so they gave us this. And h, what is the height at time t sub zero? Well, they tell us right over here. At a certain instant, the base is five meters and the height is one meter, so they give us both b and h at t sub zero, so they gave us this, they gave us this, and what is the rate of change of the height at time t sub zero?