standard_description: Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.
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?


aligns: yes