At noon joice drove to the lake at 30 mi. per hour, but she made a long walk back at 4 mi. per hour. how long did she walk ifshe was gone for 17 hours?

Distance = 30 mph * time
distance = 4 mph * time

distance = 30 mph * t
distance = 4 mph * (17-t)

Since distance is equal then
30 mph * t = 4 mph * (17-t)
 
30t = -4t + 68

34t = 68

t = 2 hours

We see the return trip time is (17 -t ) which is 15 hours.
The beginning trip time is 2 hours.

Double Check
Beginning trip = 30 miles * 2 = 60 miles
Return trip = 4 miles * 15 = 60 miles.