see the pic attached

A projector, laying on the ground, illuminates the wall of a building standing 15 m away. A person 1.8 m tall walks from the projector to the wal. We andit ike to determine the rate at which the person's shadow decreases the moment the person is 3 m from the wall, given that, at that moment, the person is walking toward the wall at 0.8 m/s. To solve this problem, let a be the distance in meters between the walker and the wall, y the height of their shadow in meters, and t the time in seconds, (a) Sketch a diagram and use similar triangles to express y as a function of I (b) What is the value of dy at the moment in question? Give its value with two decimals precision, paying attention to the sign. dt dy Number m/s dt