Evaluating piecewise functions

The  exercise appears under the Algebra I Math Mission. This exercise practices evaluating piecewise functions.

Types of Problems
There is one type of problem in this exercise:
 * 1)  Match each expression with its value.: This problem has a graph of the step function $$g(x)$$ and user is asked to match each expression with its value.
 * 2) What is the value of f(__)?: This problem has a piecewise function and user is asked to find the value of f(__).

Strategies
Knowledge of systems of equations are highly recommended to ensure success in this exercise.
 * 1) Wherever a segment ends in a full point, it means that point of the segment belongs in the graph, and wherever it ends in a hollow point, it means the point doesn't belong in the graph.
 * 2) To find the value of f(__), user needs to find the appropriate assignment rule for an input of __.

Real-life Applications

 * 1) Problems like this will appear on standardized tests, like the SATs and the ACTs.