SOLUTION
From the table given, the linear model can be drafted from what we were given after using a graphing calculator, see the image below
The linear model can be derived using

Putting in the values we have for a and b into the equation, we have

But from our data, y represents the sales S and x represents time t.
Hence the linear model becomes

Now, let's work on the quadratic model
From the calculator, we have
The quadratic model can be derived using

Putting in the values of a, b and c into the equation above, we have

So, we know y represents S and x represents t
We have the quadratic model as

The exponential model
From the graphing calculator, we have
So, from the image above, the exponential model can be derived using

From the image above, substituting the values into the equation, we have

Hence the exponential model becomes