Find the volume! Please help

How do you use the elimination method for this question? explain, because i really want to understand!

If your teacher tells you to do questions 6 through 19 in your math book for homework, how many questions is that

Amanda went into the grocery business starting with five stores. after one year, she opened two more stores. after two years, she opened two more stores than the previous year. if amanda expands her grocery business following the same pattern, which of the following graphs represents the number of stores she will own over time?