By definition we have the following equation:
t = d / v
Where,
t: time
d: distance
v: speed
For this case we have:
d / 30 + d / 4 = 17
Rewriting we have:
2d + 15d = 17 (60)
17d = 17 (60)
d = 60 mi
Then, the walking time is
t = d / v
t = 60/4
t = 15 hours
Answer:
She walked
t = 15 hours