What is 9(7x + 8) i dont understand this

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?

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9

What is ha theorem a special case of?