The ticket sales for a concert started at 4:00 P. M. The table shows the linear relationship between the number of tickets remaining and the number of hours since 4:00 P. M. Which function can be used to find y, the number of tickets remaining x hours since 4:00 P. M.?

a
y = 3,000x + 12,000
b
y = -3,000x + 12,000
c
y = -3,000x + 15,000
d
y = 3,000x + 15,000