Answer:
The second choice.
Explanation:
If we call r the number of 100 copies, then the cost of printing the first 300 copies is represented by
[tex]c(r)=12.5,r\le3[/tex]The above says that if we print less than or equal to 3 sets of 200 pages, then the cost of printing will be $12.50.
If we print more than 3 sets of 100 pages, i.e r > 3, then the price of printing is
[tex]c(r)=12.5+9(r-3),r>3[/tex]Therefore, we can combine the two sets conditions into one and say
[tex]c(r)=\begin{cases}12.5,r\le3 \\ 12.5+9(r-3),r>3\end{cases}[/tex]which is our answer!