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? Well, they tell us the height of the triangle is increasing at a rate of six meters per hour. So they tell us that as well. All of that stuff is given, and so you just have to plug it in to figure out what is the rate of change of the area at t sub zero, at that instant.