Algebra ixl question #2 ​

An architect is designing a water fountain for a park she uses the given function to model the water jet flowing from the fountain nozzles where h(x) gives the height of the water jugs in feet x feet from the starting point h(x)=-1/20x+x+15

What could explain what happened when the time was equal to 120 minutes

What is the name used to describe a graph where for some value of x, there exists 2 or more different values of y?