We have the next two equations:

And

We need to find f(3)/g(3)
First, let's find f(3):

Then g(3):

Now, the equation f(3)/g(3) :

-27/11 is the result.
a)
3 chocolate chip cookies - $2.49 .
So 1 chocolate chip cookies costs 2.49/3=$0.83
b)
1 chocolate chip cookie costs $0.83
20 chocolate chip cookies cost 0.83*20=$16.6
Full credits to a Brainley User.