Pls help me here, I need it now

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

Select all of the following expressions that are equal to 2.5.

Ze trinomial x2 + bx – c has factors of (x + m)(x – n), where m, n, and b are positive. what is ze relationship between the values of m and n? explain how you got ze answer