What is the probability of spinning a “R”?

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

Tonya paid 10$ for a new dvd in this transaction money is aa• store of valueb• medium of exchangec•unit of account

State which of the following sets of ordered pairs represent a function. set a: (5,2), (4,3), (3, 4), (2,5)set b: (-1, -6), (0, 2), (1, 2), (3, 6)set c: (2, 1), (4, 2), (2, 3), (8, 4)a. set cb. set bc. set ad. set a and set b.