Which of these sets of ordered pairs are functions?

Based upon past experience, barry expects no overdrafts. he expects no 2nd copies of statements. barry estimates that he will use network atms about 5 times a month with either bank. barry decides in the end to choose eecu. assuming that both banks provide the necessary services equally well, and based upon the tables of fees given above, how much can barry reasonably expect to save annually by choosing eecu in this case over e-town bank? a. $72 b. $78 c. $144 d. $24

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

Can someone check my answer? you : )