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

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