A 20 meter ladder is leaning against a wall. Let me draw ourselves a wall here. That is my wall. Now let me draw our 20 meter ladder. Maybe it looks something like that. That is 20 meters. They say the distance x of t between the bottom of the ladder and the wall, so it's this distance right over here, this distance right over here is x of t. They say it's increasing at a rate of three meters per minute.