Nicole walks 3 miles to her grandfather's house and later returns home on a bike. Her speed when cycling is 4 miles faster than when walking. What values for Nicole's walking speed make the total time

Nicole walks 3 miles to her grandfather's house and later returns home on a bike. Her speed when cycling is 4 miles faster than when walking. What values for Nicole's walking speed make the total time of both trips greater than 2 hours?