John has 28 cards. He gives his friend Timmy 10 cards and gave the rest to his brother. Then he gained 10 cards and lost 3. How many cards deos he have now?

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.