Question

the average cost of online photos decreases from 0.50 per print to $0.15 per print between 2002 and 2009. Find the average rate of change in the cost. Explain what it means

Answer 1

The average rate of changeis given by:
m = (y2-y1) / (x2-x1)
m = (0.50-0.15) / (2002-2009)
Rewriting:
m = (0.35) / (- 7)
m = -0.05 $ / year
Answer:
the average rate of change in the cost is:
m = -0.05 $ / year
It means that the cost per print decreases 0.05 $ per year