Your neighbor leaves his yard, which is 120 ft from the bus stop. He begins to walk toward you at the bus stop and then passes you. He walks at
a speed of 4 ft/s. His distance d from you after t seconds is given by d = 120 - 4t). After how many seconds is your neighbor 30 ft from you?
A.-22.5 s and -37.5 s
B. 22.5 s and 37.5 s
C. 30 s
D. 15 s and 45 s