Find the slope from the table

Which of these tables represents a non-linear function?

If 25% of y is 30, what is 60% of y?

Cody started biking to the park traveling 15 mph, after some time the bike got a flat so cody walked the rest of the way, traveling 4 mph. if the total trip to the park took 6 hours and it was 46 miles away, how long did cody travel at each speed? solve using rate times time= distance