Answer:
a) The slope of the graph of c is 8.34.
b) The dosage for a newborn is 8.34mg.
Step-by-step explanation:
A first order function in the following format

Has slope b.
The appropriate dosage c is a function of the age a.
In this problem, we have that:

Suppose the dosage for an adult is 200 mg. This means that 
So


(a) Find the slope of the graph of c.
The slope of the graph of c is 8.34.
(b) What is the dosage for a newborn? (Round your answer to two decimal places.)
A newborn has age a = 0. So this is c(0).


The dosage for a newborn is 8.34mg.