A spotlight on the ground shines on a wall 12 m away. If a man 2 m tall walks from the spotlight toward the building at a speed of 1.6 m/s, how fast is the length of his shadow on the building decreasing when he is 4 m from the building.

And

Find numbers that satisfy the conclusion of the mean value theorem for f(x) = x/(x-1) on [2, 5]

Thanks to anyone that answers the post!