Answer:
The average rate of change from 0 to 20 years old is -2.
Explanation:
Average rate of change means slope.
slope = y2 - y1 / x2 - x1
Pick any points between 0-20. They have given on the graph already (0, 112) and (20, 72) so plug it into slope equation.
112 - 72/ 0 - 20
40/-20
= -2
The average rate of change from 0 to 20 years old is -2.