standard_description: Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear. For example, the function A = s2 giving the area of a square as a function of its side length is not linear because its graph contains the points (1,1), (2,4) and (3,9), which are not on a straight line.
problem_activity: Task
Anna and Jason have summer jobs stuffing envelopes for two different companies. Anna earns \$14 for every 400 envelops she finishes. Jason earns \$9 for every 300 envelopes he finishes.
Draw graphs and write equations that show the earnings, $y$ as functions of the number of envelopes stuffed, $n$ for Anna and Jason.
Who makes more from stuffing the same number of envelopes? How can you tell this from the graph?
Suppose Anna has savings of \$100 at the beginning of the summer and she saves all her earnings from her job. Graph her savings as a function of the number of envelopes she stuffed, $n$. How does this graph compare to her previous earnings graph? What is the meaning of the slope in each case?


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