Which car is traveling at a greater speed? Pls help guys

The maximum depth that he will reach is -125 meters.

The first thing you should realize is that this is a quadratic equation and the graph will be a parabola.

We can simply the equation to:

y = (1/20)x^2 - 5x

Now, use -b/2a to find the x-value of the vertex which is 50. Then, input 50 back into the equation to get -125 for the maximum depth.