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
d. 15 s and 45 s