Andrea has a part-time job at the local grocery store. She saves for her vacation at a rate of $15 every week. Find her rate of change.
Solution
Begin by finding two ordered pairs. You can make a chart or use the Substitution Property to find two
coordinates. After 2 weeks of saving, she will have $30. After 10 weeks of saving, she will have $150. So we will use
the points (2, ) and (10, to determine our slope.
Use the formula:
M=
m =
150-30 dollars
10-2 weeks
m =
dollars
weeks
15 dollars
1 week
Andrea's rate of change is $15 per week.
m =