Answer
t = 4.444 seconds or t = 17.77 seconds
Work Step by Step
abs(200−18t)=d
We want a distance of 120 feet (and also -120 feet, as my friend would still be deemed 120 feet away from me).
200−18t=120
200−18t−120+18t=120−120+18t
80=18t
80/18=18t/18
4.444=t
200−18t=−120
200−18t+120+18t=−120+120+18t
320=18t
320/18=18t/18
17.77=t
