Who is the tallest person in the world

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

Consider that lines b and c are parallel. what is the value of x? what is the measure of the smaller angle?

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.