Meters per minute, so they give us that piece of information. The rate of change of x with respect to time, they give us that. At a certain instant, t sub zero, the top of the ladder is a distance of 15 meters. The top of the ladder, so let's make this very clear. This distance right over here is y of t, y of t. They say at time t sub zero, y of t is 15 meters. Let me just write it here. Y of t sub zero is equal to 15 meters.