What is the average (arithmetic mean) of 4x - 3 and 2x + 5?

A. X-4

B. 2x - 8

C. 3x + 1

D. 6x + 2

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.