What is 4 divided by 3.5

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.

How to simply and write the answer n a whole number

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)