The first thing you should do in this case is to represent the distance of "the monster Zip line" by a function.
 The function for this case is:
 D = 120h
 Where,
 D: distance in kilometers.
 h: time in hour.
 Substituting the values we have:
 D = 120 * (0.25) = 30 Km
 answer:
 You could travel on the Monster Zip line 30 Km in 0.25 hours