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
Lena paid \$18.96 for 3 pounds of coffee.
What is the cost per pound for this coffee?
How many pounds of coffee could she buy for \$1.00?
Draw a graph in the coordinate plane of the relationship between the number of pounds of coffee and the total cost.
In this situation, what is the meaning of the slope of the line you drew in part (c)?


aligns: no