Consider the function of $f(x)=\frac{2}{7-x}$.

1. What is $f(7)$?

   Hint (a):

   Substitute $7\ \text{for}\ x$.

2. What is the domain of $f(x)$?

   Hint (b):

   Division by $0$ is undefined. What x-value causes division by $0$ for this function?
   $x$ cannot have that value.

3. If $g(x)=2x+5$, what is $g(3)$?

   Hint (c):

   Substitute $3\ \text{for}\ x$.

4. Now use the output of $g(3)$ as the input for $f$ to calculate $f(g(3))$.

   Hint (d):

   $g(3)=11$, therefore calculate $f(11)$.