Pierre is an artist. Last week he bought 5 brushes and 6 tubes of paint for $43. This week he bought 12 tubes of paint and 4 brushes for $56. What is the cost of one brush? What is the cost of one tube of paint?

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.