I just don't understand these!

I can't get number one to show up on my graphing calculator (even when i change the window proportions), and number two...what?? If anyone can show their work and provide explanations so I can understand/learn these concepts, please, please, please do so!

**QUESTIONS:**
1.)

**"use a graphing utility to graph the sales function over 1 year, where S is the sales in thousands of units and 't' is the time in months, with t=1 corresponding to January. Determine the months of maximum and minimum sales."**
[snip]