Answer:
Part A) The proportional equation is
Part B) 8 hours of training
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
Let
c -----> the cost to hire a dog
h ----> the amount of time in hours
The linear equation is equal to
Sue spent $660 on 12 hours of obedience training for her dog Muffin
Find the value of k (constant of proportionality)

substitute the values

therefore
The linear equation is
For 
Find the value of h
substitute in the equation and solve for h