options: Calculate and interpret the average rate of change of a function (presented symbolically or as a table) over a specified interval. Estimate the rate of change from a graph.

For a function that models a relationship between two quantities, interpret key features of graphs and tables in terms of the quantities, and sketch graphs showing key features given a verbal description of the relationship. Key features include: intercepts; intervals where the function is increasing, decreasing, positive, or negative; relative maximums and minimums; symmetries; end behavior; and periodicity.

Relate the domain of a function to its graph and, where applicable, to the quantitative relationship it describes.  For example, if the function h(n) gives the number of person-hours it takes to assemble n engines in a factory, then the positive integers would be an appropriate domain for the function.
problem_activity: When Janaya started working, she researched how income tax was determined. She read that income up to and including $10,000 is taxed at a rate of 10%. Any income over $10,000 and up to and including $40,000 is taxed at a rate of 15%. For example, if Janaya earned $11,000 in one year, the first $10,000 would be taxed at a rate of 10% and the last $1,000 would be taxed at a rate of 15%.
How much income tax would Janaya pay if she earned $15,000 in one year?
Write a piecewise function to represent the situation.
How much more income tax would a person who earns $30,000 pay than a person who earns $10,000 in one year?


correct_option_index: 2