Need help finding efg

Need on this geometry question. explain how you did it.

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.

If rs 900 amounts to rs 1044 in 4 years, what sum will amount to 1368 in 3 1/2 years at the same rate