w=5a +16.5
A pediatrician uses the model above to estimate
the weight w of a child, in pounds, in the terms of the
child's age a, in years, between the ages of 2 and 8.
Based on the model, what is the estimated increase,
in pounds, of a child's weight each year?

1.=5
2.=6.7
3.=16.5
4.=26.5