Systems of equations with graphing

Add the fractions and simplify 1/2+ 1/3

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

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.