I already have the answer to the second question I just need the answer to the first one can anyone help??

The correct answer is A) The total cost of 3 cookies is $9.00

We can tell this is the correct answer by looking at the notation. When you see an f(x) expression replaced with a number in the parenthesis, like f(3), the number in the parenthesis is what we are using for x. It says in the description that x = cookies, so since we can tell x = 3, we know we have 3 cookies. 

Also, in cases such as this, we know that total cost is f(x). Even though we put a number in the parenthesis for it, that doesn't chance that it equals cost. So, since f(x)/f(3) = cost and it is listed as equal to 9, we know that the overall cost is $9.00.